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Umnajkitikorn K, Boonchuen P, Senavongse R, Tongta S, Tian Y, Hu Y, Petersen BL, Blennow A. Transcriptomics and starch biosynthesis analysis in leaves and developing seeds of mung bean provide a basis for genetic engineering of starch composition and seed quality. FRONTIERS IN PLANT SCIENCE 2024; 15:1332150. [PMID: 38751837 PMCID: PMC11094274 DOI: 10.3389/fpls.2024.1332150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 04/02/2024] [Indexed: 05/18/2024]
Abstract
Mung bean starch is distinguished by its exceptional high amylose content and regulation of starch biosynthesis in leaves and storage tissues, such as seeds, share considerable similarities. Genetic engineering of starch composition and content, requires detailed knowledge of starch biosynthetic gene expression and enzymatic regulation. In this study we applied detailed transcriptomic analyses to unravel the global differential gene expression patterns in mung bean leaves and in seeds during various stages of development. The objective was to identify candidate genes and regulatory mechanisms that may enable generation of desirable seed qualities through the use of genetic engineering. Notable differences in gene expression, in particular low expression of the Protein Targeting to Starch (PTST), starch synthase (SS) 3, and starch branching enzyme1 (SBE1) encoding genes in developing seeds as compared to leaves were evident. These differences were related to starch molecular structures and granule morphologies. Specifically, the starch molecular size distribution at different stages of seed development correlated with the starch biosynthesis gene expression of the SBE1, SS1, granule-bound starch synthases (GBSS) and isoamylase 1 (ISA1) encoding genes. Furthermore, putative hormonal and redox controlled regulation were observed, which may be explained by abscisic acid (ABA) and indole-3-acetic acid (IAA) induced signal transduction, and redox regulation of ferredoxins and thioredoxins, respectively. The morphology of starch granules in leaves and developing seeds were clearly distinguishable and could be correlated to differential expression of SS1. Here, we present a first comprehensive transcriptomic dataset of developing mung bean seeds, and combined these findings may enable generation of genetic engineering strategies of for example starch biosynthetic genes for increasing starch levels in seeds and constitute a valuable toolkit for improving mung bean seed quality.
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Affiliation(s)
- Kamolchanok Umnajkitikorn
- School of Crop Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Pakpoom Boonchuen
- School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Rattanavalee Senavongse
- School of Crop Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Sunanta Tongta
- School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Yu Tian
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Yaqi Hu
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Bent Larsen Petersen
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Andreas Blennow
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
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Yu J, Yang J, Dai S, Xie N, Tang Y, Pi S, Zhu M. PpAmy1 Plays a Role in Fruit-Cracking by Regulating Mesocarp Starch Hydrolysis of Nectarines. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:2667-2677. [PMID: 38287914 DOI: 10.1021/acs.jafc.3c07985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
Nectarine [Prunus persica (L.) Batsch var.] fruits are highly susceptible to cracking during the ripening process, which significantly decreases their commercial value. In this study, we investigated the underlying mechanism of nectarine fruit-cracking using two nectarine varieties, namely, "Qiannianhong" (cracking-susceptible) and "CR1012" (cracking-resistant). Our findings indicate that nectarine fruit-cracking occurs during the second stage of fruit expansion. Despite no differences in epicarp cell size between "Qiannianhong" and "CR1012", the mesocarp cells of "Qiannianhong" were larger than those of "CR1012". Moreover, a comparison of starch hydrolysis between the two varieties revealed that "CR1012" had higher starch content in the mesocarp but lower soluble sugar content compared to "Qiannianhong". Additionally, by testing the α-amylase and β-amylase activity of the mesocarp, our results showed a difference only in α-amylase activity between the two varieties. Furthermore, qRT-PCR detection indicated a higher expression level of the PpAmy1 (α-amylase synthesis gene) in "Qiannianhong" compared to "CR1012". To further investigate the role of PpAmy1, we employed RNAi technology to suppress its expression in "Qiannianhong" fruits. The results showed a significant reduction in α-amylase activity, starch hydrolysis, soluble sugar content, cell size of the mesocarp, and fruit-cracking. These findings underscore the pivotal role of PpAmy1 in the occurrence of nectarine fruit cracking.
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Affiliation(s)
- Jun Yu
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
- College of Coastal Agriculture Sciences, Guangdong Ocean University, Zhanjiang 524088, China
| | - Jiangheng Yang
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Shuoyue Dai
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Ningzhen Xie
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Yuenan Tang
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Shuiqin Pi
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
| | - Mingtao Zhu
- College of Agriculture and Biotechnology, Hunan University of Humanities, Science and Technology, Loudi 417000, China
- College of Coastal Agriculture Sciences, Guangdong Ocean University, Zhanjiang 524088, China
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Ma M, Zhong W, Zhang Q, Deng L, Wen J, Yi B, Tu J, Fu T, Zhao L, Shen J. Genome-wide analysis of transcriptome and histone modifications in Brassica napus hybrid. FRONTIERS IN PLANT SCIENCE 2023; 14:1123729. [PMID: 36778699 PMCID: PMC9911877 DOI: 10.3389/fpls.2023.1123729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
Although utilization of heterosis has largely improved the yield of many crops worldwide, the underlying molecular mechanism of heterosis, particularly for allopolyploids, remains unclear. Here, we compared epigenome and transcriptome data of an elite hybrid and its parental lines in three assessed tissues (seedling, flower bud, and silique) to explore their contribution to heterosis in allopolyploid B. napus. Transcriptome analysis illustrated that a small proportion of non-additive genes in the hybrid compared with its parents, as well as parental expression level dominance, might have a significant effect on heterosis. We identified histone modification (H3K4me3 and H3K27me3) variation between the parents and hybrid, most of which resulted from the differences between parents. H3K4me3 variations were positively correlated with gene expression differences among the hybrid and its parents. Furthermore, H3K4me3 and H3K27me3 were rather stable in hybridization and were mainly inherited additively in the B. napus hybrid. Together, our data revealed that transcriptome reprogramming and histone modification remodeling in the hybrid could serve as valuable resources for better understanding heterosis in allopolyploid crops.
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Li R, Zheng W, Jiang M, Zhang H. A review of starch biosynthesis in cereal crops and its potential breeding applications in rice ( Oryza Sativa L.). PeerJ 2022; 9:e12678. [PMID: 35036154 PMCID: PMC8710062 DOI: 10.7717/peerj.12678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/02/2021] [Indexed: 11/20/2022] Open
Abstract
Starch provides primary storage of carbohydrates, accounting for approximately 85% of the dry weight of cereal endosperm. Cereal seeds contribute to maximum annual starch production and provide the primary food for humans and livestock worldwide. However, the growing demand for starch in food and industry and the increasing loss of arable land with urbanization emphasizes the urgency to understand starch biosynthesis and its regulation. Here, we first summarized the regulatory signaling pathways about leaf starch biosynthesis. Subsequently, we paid more attention to how transcriptional factors (TFs) systematically respond to various stimulants via the regulation of the enzymes during starch biosynthesis. Finally, some strategies to improve cereal yield and quality were put forward based on the previous reports. This review would collectively help to design future studies on starch biosynthesis in cereal crops.
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Affiliation(s)
- Ruiqing Li
- State Key Laboratory of Rice Biology and Chinese National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, China.,College of Agronomy, Anhui Agricultural University, Hefei, China
| | - Wenyin Zheng
- College of Agronomy, Anhui Agricultural University, Hefei, China
| | - Meng Jiang
- State Key Laboratory of Rice Biology, Institute of Crop Sciences, Zhejiang University, Hangzhou, China
| | - Huali Zhang
- State Key Laboratory of Rice Biology and Chinese National Center for Rice Improvement, China National Rice Research Institute, Hangzhou, China
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Wang Z, Wei K, Xiong M, Wang J, Zhang C, Fan X, Huang L, Zhao D, Liu Q, Li Q. Glucan, Water-Dikinase 1 (GWD1), an ideal biotechnological target for potential improving yield and quality in rice. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:2606-2618. [PMID: 34416068 PMCID: PMC8633486 DOI: 10.1111/pbi.13686] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 05/07/2023]
Abstract
The source-sink relationship determines the overall agronomic performance of rice. Cloning and characterizing key genes involved in the regulation of source and sink dynamics is imperative for improving rice yield. However, few source genes with potential application in rice have been identified. Glucan, Water-Dikinase 1 (GWD1) is an essential enzyme that plays a pivotal role in the first step of transitory starch degradation in source tissues. In the present study, we successfully generated gwd1 weak mutants by promoter editing using CRISPR/Cas9 system, and also leaf-dominant overexpression lines of GWD1 driven by Osl2 promoter. Analysis of the gwd1 plants indicated that promoter editing mediated down-regulation of GWD1 caused no observable effects on rice growth and development, but only mildly modified its grain transparency and seed germination. However, the transgenic pOsl2::GWD1 overexpression lines showed improvements in multiple key traits, including rice yield, grain shape, rice quality, seed germination and stress tolerance. Therefore, our study shows that GWD1 is not only involved in transitory starch degradation in source tissues, but also plays key roles in the seeds, which is a sink tissue. In conclusion, we find that GWD1 is an ideal biotechnological target with promising potential for the breeding of elite rice cultivars via genetic engineering.
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Affiliation(s)
- Zhen Wang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
| | - Ke Wei
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
| | - Min Xiong
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
| | - Jin‐Dong Wang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
| | - Chang‐Quan Zhang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
| | - Xiao‐Lei Fan
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
| | - Li‐Chun Huang
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
| | - Dong‐Sheng Zhao
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
| | - Qiao‐Quan Liu
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
| | - Qian‐Feng Li
- Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding /Key Laboratory of Plant Functional Genomics of the Ministry of EducationCollege of AgricultureYangzhou UniversityYangzhouJiangsuChina
- Co‐Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province / Jiangsu Key Laboratory of Crop Genetics and PhysiologyYangzhou UniversityYangzhouJiangsuChina
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Díaz P, Sarmiento F, Mathew B, Ballvora A, Mosquera Vásquez T. Genomic regions associated with physiological, biochemical and yield-related responses under water deficit in diploid potato at the tuber initiation stage revealed by GWAS. PLoS One 2021; 16:e0259690. [PMID: 34748612 PMCID: PMC8575265 DOI: 10.1371/journal.pone.0259690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/24/2021] [Indexed: 11/19/2022] Open
Abstract
Water deficit, which is increasing with climate change, is a serious threat to agricultural sustainability worldwide. Dissection of the genetic architecture of water deficit responses is highly desirable for developing water-deficit tolerant potato cultivars and enhancing the resilience of existing cultivars. This study examined genetic variation in response to water deficit in a panel of diploid potato and identified the QTL governing this trait via a genome-wide association study (GWAS). A panel of 104 diploid potato accessions were evaluated under both well-watered and water deficit treatments at tuber initiation stage. Drought stress index (DTI) was calculated to assess tolerance of the diploid potato genotypes to water deficit. The GWAS was conducted using a matrix of 47K single nucleotide polymorphisms (SNP), recently available for this population. We are reporting 38 QTL, seven for well-watered conditions, twenty-two for water deficit conditions and nine for DTI which explain between 12.6% and 44.1% of the phenotypic variance. A set of 6 QTL were found to be associated with more than one variable. Marker WDP-9.21 was found associated with tuber fresh weigh under WD and gene annotation analysis revealed co-localization with the Glucan/water dikinase (GWD) gene. Of the nine QTL detected from DTI on chromosomes 2,3,5,8,10 and 12, three candidate genes with a feasible role in water deficit response were identified. The findings of this study can be used in marker-assisted selection (MAS) for water- deficit tolerance breeding in potato.
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Affiliation(s)
- Paula Díaz
- Departamento de Agronomía, Facultad de Ciencias Agrarias, Universidad Nacional de Colombia-Sede Bogotá, Bogotá, Colombia
| | - Felipe Sarmiento
- Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia-Sede Bogotá, Bogotá, Colombia
| | - Boby Mathew
- Bayer CropScience, Monheim am Rhein, Germany
| | - Agim Ballvora
- Institute of Crop Science and Resource Conservation Plant Breeding, University of Bonn, Bonn, Germany
| | - Teresa Mosquera Vásquez
- Departamento de Agronomía, Facultad de Ciencias Agrarias, Universidad Nacional de Colombia-Sede Bogotá, Bogotá, Colombia
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Adegoke TV, Wang Y, Chen L, Wang H, Liu W, Liu X, Cheng YC, Tong X, Ying J, Zhang J. Posttranslational Modification of Waxy to Genetically Improve Starch Quality in Rice Grain. Int J Mol Sci 2021; 22:4845. [PMID: 34063649 PMCID: PMC8124582 DOI: 10.3390/ijms22094845] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 01/07/2023] Open
Abstract
The waxy (Wx) gene, encoding the granule-bound starch synthase (GBSS), is responsible for amylose biosynthesis and plays a crucial role in defining eating and cooking quality. The waxy locus controls both the non-waxy and waxy rice phenotypes. Rice starch can be altered into various forms by either reducing or increasing the amylose content, depending on consumer preference and region. Low-amylose rice is preferred by consumers because of its softness and sticky appearance. A better way of improving crops other than downregulation and overexpression of a gene or genes may be achieved through the posttranslational modification of sites or regulatory enzymes that regulate them because of their significance. The impact of posttranslational GBSSI modifications on extra-long unit chains (ELCs) remains largely unknown. Numerous studies have been reported on different crops, such as wheat, maize, and barley, but the rice starch granule proteome remains largely unknown. There is a need to improve the yield of low-amylose rice by employing posttranslational modification of Wx, since the market demand is increasing every day in order to meet the market demand for low-amylose rice in the regional area that prefers low-amylose rice, particularly in China. In this review, we have conducted an in-depth review of waxy rice, starch properties, starch biosynthesis, and posttranslational modification of waxy protein to genetically improve starch quality in rice grains.
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Affiliation(s)
- Tosin Victor Adegoke
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yifeng Wang
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Lijuan Chen
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Huimei Wang
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Wanning Liu
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Xingyong Liu
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Yi-Chen Cheng
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Xiaohong Tong
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Jiezheng Ying
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
| | - Jian Zhang
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou 311400, China; (T.V.A.); (Y.W.); (L.C.); (H.W.); (W.L.); (X.L.); (Y.-C.C.); (X.T.); (J.Y.)
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You Y, Zhang M, Yang W, Li C, Liu Y, Li C, He J, Wu W. Starch phosphorylation and the in vivo regulation of starch metabolism and characteristics. Int J Biol Macromol 2020; 159:823-831. [PMID: 32445823 DOI: 10.1016/j.ijbiomac.2020.05.156] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/17/2020] [Accepted: 05/18/2020] [Indexed: 12/26/2022]
Abstract
Starch is the most significant carbon and energy reserve in plants and is also a sustainable feedstock for many industrial applications. Substantial research effort has been devoted to enhancing the yield and quality of starch. Over the past century, starch phosphorylation has aroused increasing interest as the only naturally occurring covalent modification in starch. Many studies have investigated the role of phosphorylation in starch metabolism and its impact on the starch granule. In this review, the two key enzymes involved in starch phosphorylation and their catalytic mechanisms are described at the molecular level; the vital roles of phosphorylation in starch degradation and biosynthesis are illuminated in detail; and the multiple influences of phosphorylation on starch composition, granule structure and physicochemical properties are discussed. This review systematically summarizes the importance of phosphorylation in starch metabolism, and describes the advanced methods used to precisely measure phosphate and increase the level of starch phosphorylation.
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Affiliation(s)
- Yuxian You
- College of Food Science, Sichuan Agricultural University, Yaan 625014, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Mingyue Zhang
- College of Food Science, Sichuan Agricultural University, Yaan 625014, China
| | - Wen Yang
- College of Food Science, Sichuan Agricultural University, Yaan 625014, China
| | - Cheng Li
- College of Food Science, Sichuan Agricultural University, Yaan 625014, China
| | - Yuntao Liu
- College of Food Science, Sichuan Agricultural University, Yaan 625014, China.
| | - Caiming Li
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
| | - Jialiang He
- School of Food and Bioengineering, Henan University of Science and Technology, Luoyang 471023, China
| | - Wenjuan Wu
- College of Science, Sichuan Agricultural University, Yaan 625014, China
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Smith AM, Zeeman SC. Starch: A Flexible, Adaptable Carbon Store Coupled to Plant Growth. ANNUAL REVIEW OF PLANT BIOLOGY 2020; 71:217-245. [PMID: 32075407 DOI: 10.1146/annurev-arplant-050718-100241] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Research in the past decade has uncovered new and surprising information about the pathways of starch synthesis and degradation. This includes the discovery of previously unsuspected protein families required both for processes and for the long-sought mechanism of initiation of starch granules. There is also growing recognition of the central role of leaf starch turnover in making carbon available for growth across the day-night cycle. Sophisticated systems-level control mechanisms involving the circadian clock set rates of nighttime starch mobilization that maintain a steady supply of carbon until dawn and modulate partitioning of photosynthate into starch in the light, optimizing the fraction of assimilated carbon that can be used for growth. These discoveries also uncover complexities: Results from experiments with Arabidopsis leaves in conventional controlled environments are not necessarily applicable to other organs or species or to growth in natural, fluctuating environments.
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Affiliation(s)
| | - Samuel C Zeeman
- Institute of Plant Molecular Biology, ETH Zürich, 8092 Zürich, Switzerland
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Carrillo JB, Torresi F, Morales LL, Ricordi M, Gomez-Casati DF, Busi MV, Martín M. Identification and characterization of ChlreSEX4, a novel glucan phosphatase from Chlamydomonas reinhardtii green alga. Arch Biochem Biophys 2020; 680:108235. [PMID: 31877265 DOI: 10.1016/j.abb.2019.108235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 12/18/2019] [Accepted: 12/20/2019] [Indexed: 11/16/2022]
Abstract
Chlamydomonas reinhardtii is the best known unicellular green alga model which has long been used to investigate all kinds of cellular processes, including starch metabolism. Here we identified and characterized a novel enzyme, ChlreSEX4, orthologous to glucan phosphatase SEX4 from Arabidopsis thaliana, that is capable of binding and dephosphorylating amylopectin in vitro. We also reported that cysteine 224 and tryptophan 305 residues are critical for enzyme catalysis and substrate binding. Furthermore, we verified that ChlreSEX4 gene is expressed in vivo and that glucan phosphatase activity is measurable in Chlamydomonas protein extracts. In view of the results presented, we suggest ChlreSEX4 as a functional phosphoglucan phosphatase from C. reinhardtii. Our data obtained so far contribute to understanding the phosphoglucan phosphatases evolutionary process in the green lineage and their role in starch reversible phosphorylation. In addition, this allows to position Chlamydomonas as a potential tool to obtain starches with different degrees of phosphorylation for industrial or biotechnological purposes.
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Affiliation(s)
- Julieta B Carrillo
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Florencia Torresi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Luisina L Morales
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Micaela Ricordi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Diego F Gomez-Casati
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina
| | - Maria V Busi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina.
| | - Mariana Martín
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, 2000, Rosario, Santa Fe, Argentina.
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Monroe JD. Involvement of five catalytically active Arabidopsis β-amylases in leaf starch metabolism and plant growth. PLANT DIRECT 2020; 4:e00199. [PMID: 32072133 PMCID: PMC7011640 DOI: 10.1002/pld3.199] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 12/16/2019] [Accepted: 12/27/2019] [Indexed: 05/14/2023]
Abstract
Starch degradation in chloroplasts requires β-amylase (BAM) activity, but in Arabidopsis, there are nine BAM proteins, five of which are thought to be catalytic. Although single-gene knockouts revealed the necessity of BAM3 for starch degradation, contributions of other BAMs are poorly understood. Moreover, it is not possible to detect the contribution of individual BAMs in plants containing multiple active BAMs. Therefore, we constructed a set of five quadruple mutants each expressing only one catalytically active BAM, and a quintuple mutant missing all of these BAMs (B-Null). Using these mutants, we assessed the influence of each individual BAM on plant growth and on leaf starch degradation. Both BAM1 and BAM3 alone support wild-type (WT) levels of growth. BAM3 alone is sufficient to degrade leaf starch completely whereas BAM1 alone can only partially degrade leaf starch. In contrast, BAM2, BAM5, and BAM6 have no detectable effect on starch degradation or plant growth, being comparable with the B-Null plants. B-Null plant extracts contained no measurable amylase activity, whereas BAM3 and BAM1 contributed about 70% and 14% of the WT activity, respectively. BAM2 activity was low but detectable and BAM6 contributed no measurable activity. Interestingly, activity of BAM1 and BAM3 in the mutants varied little developmentally or diurnally, and did not increase appreciably in response to osmotic or cold stress. With these genetic lines, we now have new opportunities to investigate members of this diverse gene family.
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12
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Ancín M, Larraya L, Fernández-San Millán A, Veramendi J, Burch-Smith T, Farran I. NTRC and Thioredoxin f Overexpression Differentially Induces Starch Accumulation in Tobacco Leaves. PLANTS 2019; 8:plants8120543. [PMID: 31779140 PMCID: PMC6963466 DOI: 10.3390/plants8120543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 11/16/2022]
Abstract
Thioredoxin (Trx) f and NADPH-dependent Trx reductase C (NTRC) have both been proposed as major redox regulators of starch metabolism in chloroplasts. However, little is known regarding the specific role of each protein in this complex mechanism. To shed light on this point, tobacco plants that were genetically engineered to overexpress the NTRC protein from the chloroplast genome were obtained and compared to previously generated Trx f-overexpressing transplastomic plants. Likewise, we investigated the impact of NTRC and Trx f deficiency on starch metabolism by generating Nicotiana benthamiana plants that were silenced for each gene. Our results demonstrated that NTRC overexpression induced enhanced starch accumulation in tobacco leaves, as occurred with Trx f. However, only Trx f silencing leads to a significant decrease in the leaf starch content. Quantitative analysis of enzyme activities related to starch synthesis and degradation were determined in all of the genotypes. Zymographic analyses were additionally performed to compare the amylolytic enzyme profiles of both transplastomic tobacco plants. Our findings indicated that NTRC overexpression promotes the accumulation of transitory leaf starch as a consequence of a diminished starch turnover during the dark period, which seems to be related to a significant reductive activation of ADP-glucose pyrophosphorylase and/or a deactivation of a putative debranching enzyme. On the other hand, increased starch content in Trx f-overexpressing plants was connected to an increase in the capacity of soluble starch synthases during the light period. Taken together, these results suggest that NTRC and the ferredoxin/Trx system play distinct roles in starch turnover.
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Affiliation(s)
- María Ancín
- Institute for Multidisciplinary Research in Applied Biology, UPNA, 31006 Pamplona, Spain; (M.A.); (L.L.); (A.F.-S.M.); (J.V.)
| | - Luis Larraya
- Institute for Multidisciplinary Research in Applied Biology, UPNA, 31006 Pamplona, Spain; (M.A.); (L.L.); (A.F.-S.M.); (J.V.)
| | - Alicia Fernández-San Millán
- Institute for Multidisciplinary Research in Applied Biology, UPNA, 31006 Pamplona, Spain; (M.A.); (L.L.); (A.F.-S.M.); (J.V.)
| | - Jon Veramendi
- Institute for Multidisciplinary Research in Applied Biology, UPNA, 31006 Pamplona, Spain; (M.A.); (L.L.); (A.F.-S.M.); (J.V.)
| | - Tessa Burch-Smith
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA;
| | - Inmaculada Farran
- Institute for Multidisciplinary Research in Applied Biology, UPNA, 31006 Pamplona, Spain; (M.A.); (L.L.); (A.F.-S.M.); (J.V.)
- Correspondence: ; Tel.: +34-948-168-034
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13
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Mdodana NT, Jewell JF, Phiri EE, Smith ML, Oberlander K, Mahmoodi S, Kossmann J, Lloyd JR. Mutations in Glucan, Water Dikinase Affect Starch Degradation and Gametophore Development in the Moss Physcomitrella patens. Sci Rep 2019; 9:15114. [PMID: 31641159 PMCID: PMC6805951 DOI: 10.1038/s41598-019-51632-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 10/01/2019] [Indexed: 11/23/2022] Open
Abstract
The role of starch degradation in non-vascular plants is poorly understood. To expand our knowledge of this area, we have studied this process in Physcomitrella patens. This has been achieved through examination of the step known to initiate starch degradation in angiosperms, glucan phosphorylation, catalysed by glucan, water dikinase (GWD) enzymes. Phylogenetic analysis indicates that GWD isoforms can be divided into two clades, one of which contains GWD1/GWD2 and the other GWD3 isoforms. These clades split at a very early stage within plant evolution, as distinct sequences that cluster within each were identified in all major plant lineages. Of the five genes we identified within the Physcomitrella genome that encode GWD-like enzymes, two group within the GWD1/GWD2 clade and the others within the GWD3 clade. Proteins encoded by both loci in the GWD1/GWD2 clade, named PpGWDa and PpGWDb, are localised in plastids. Mutations of either PpGWDa or PpGWDb reduce starch phosphate abundance, however, a mutation at the PpGWDa locus had a much greater influence than one at PpGWDb. Only mutations affecting PpGWDa inhibited starch degradation. Mutants lacking this enzyme also failed to develop gametophores, a phenotype that could be chemically complemented using glucose supplementation within the growth medium.
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Affiliation(s)
- Ntombizanele T Mdodana
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Jonathan F Jewell
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Ethel E Phiri
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Marthinus L Smith
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Kenneth Oberlander
- Schweickerdt Herbarium, Department of Plant and Soil Sciences, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Saire Mahmoodi
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
| | - James R Lloyd
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa.
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14
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Flis A, Mengin V, Ivakov AA, Mugford ST, Hubberten HM, Encke B, Krohn N, Höhne M, Feil R, Hoefgen R, Lunn JE, Millar AJ, Smith AM, Sulpice R, Stitt M. Multiple circadian clock outputs regulate diel turnover of carbon and nitrogen reserves. PLANT, CELL & ENVIRONMENT 2019; 42:549-573. [PMID: 30184255 DOI: 10.1111/pce.13440] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 08/27/2018] [Accepted: 08/31/2018] [Indexed: 05/09/2023]
Abstract
Plants accumulate reserves in the daytime to support growth at night. Circadian regulation of diel reserve turnover was investigated by profiling starch, sugars, glucose 6-phosphate, organic acids, and amino acids during a light-dark cycle and after transfer to continuous light in Arabidopsis wild types and in mutants lacking dawn (lhy cca1), morning (prr7 prr9), dusk (toc1, gi), or evening (elf3) clock components. The metabolite time series were integrated with published time series for circadian clock transcripts to identify circadian outputs that regulate central metabolism. (a) Starch accumulation was slower in elf3 and prr7 prr9. It is proposed that ELF3 positively regulates starch accumulation. (b) Reducing sugars were high early in the T-cycle in elf3, revealing that ELF3 negatively regulates sucrose recycling. (c) The pattern of starch mobilization was modified in all five mutants. A model is proposed in which dawn and dusk/evening components interact to pace degradation to anticipated dawn. (d) An endogenous oscillation of glucose 6-phosphate revealed that the clock buffers metabolism against the large influx of carbon from photosynthesis. (e) Low levels of organic and amino acids in lhy cca1 and high levels in prr7 prr9 provide evidence that the dawn components positively regulate the accumulation of amino acid reserves.
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Affiliation(s)
- Anna Flis
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Virginie Mengin
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Alexander A Ivakov
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Sam T Mugford
- John Innes Centre, Norwich Research Park, Norwich, UK
| | | | - Beatrice Encke
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Nicole Krohn
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Melanie Höhne
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Regina Feil
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Rainer Hoefgen
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - John E Lunn
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Andrew J Millar
- SynthSys and School of Biological Sciences, C.H. Waddington Building, University of Edinburgh, Edinburgh, UK
| | | | - Ronan Sulpice
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
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15
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Lloyd JR, Kossmann J. Starch Trek: The Search for Yield. FRONTIERS IN PLANT SCIENCE 2019; 9:1930. [PMID: 30719029 PMCID: PMC6348371 DOI: 10.3389/fpls.2018.01930] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/12/2018] [Indexed: 05/27/2023]
Abstract
Starch is a plant storage polyglucan that accumulates in plastids. It is composed of two polymers, amylose and amylopectin, with different structures and plays several roles in helping to determine plant yield. In leaves, it acts as a buffer for night time carbon starvation. Genetically altered plants that cannot synthesize or degrade starch efficiently often grow poorly. There have been a number of successful approaches to manipulate leaf starch metabolism that has resulted in increased growth and yield. Its degradation is also a source of sugars that can help alleviate abiotic stress. In edible parts of plants, starch often makes up the majority of the dry weight constituting much of the calorific value of food and feed. Increasing starch in these organs can increase this as well as increasing yield. Enzymes involved in starch metabolism are well known, and there has been much research analyzing their functions in starch synthesis and degradation, as well as genetic and posttranslational regulatory mechanisms affecting them. In this mini review, we examine work on this topic and discuss future directions that could be used to manipulate this metabolite for improved yield.
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Affiliation(s)
| | - Jens Kossmann
- Department of Genetics, Institute for Plant Biotechnology, University of Stellenbosch, Stellenbosch, South Africa
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16
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Wilkens C, Svensson B, Møller MS. Functional Roles of Starch Binding Domains and Surface Binding Sites in Enzymes Involved in Starch Biosynthesis. FRONTIERS IN PLANT SCIENCE 2018; 9:1652. [PMID: 30483298 PMCID: PMC6243121 DOI: 10.3389/fpls.2018.01652] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/24/2018] [Indexed: 05/07/2023]
Abstract
Biosynthesis of starch is catalyzed by a cascade of enzymes. The activity of a large number of these enzymes depends on interaction with polymeric substrates via carbohydrate binding sites, which are situated outside of the catalytic site and its immediate surroundings including the substrate-binding crevice. Such secondary binding sites can belong to distinct starch binding domains (SBDs), classified as carbohydrate binding modules (CBMs), or be surface binding sites (SBSs) exposed on the surface of catalytic domains. Currently in the Carbohydrate-Active enZYmes (CAZy) database SBDs are found in 13 CBM families. Four of these families; CBM20, CBM45, CBM48, and CBM53 are represented in enzymes involved in starch biosynthesis, namely starch synthases, branching enzymes, isoamylases, glucan, water dikinases, and α-glucan phosphatases. A critical role of the SBD in activity has not been demonstrated for any of these enzymes. Among the well-characterized SBDs important for starch biosynthesis are three CBM53s of Arabidopsis thaliana starch synthase III, which have modest affinity. SBSs, which are overall less widespread than SBDs, have been reported in some branching enzymes, isoamylases, synthases, phosphatases, and phosphorylases active in starch biosynthesis. SBSs appear to exert roles similar to CBMs. SBSs, however, have also been shown to modulate specificity for example by discriminating the length of chains transferred by branching enzymes. Notably, the difference in rate of occurrence between SBDs and SBSs may be due to lack of awareness of SBSs. Thus, SBSs as opposed to CBMs are not recognized at the protein sequence level, which hampers their identification. Moreover, only a few SBSs in enzymes involved in starch biosynthesis have been functionally characterized, typically by structure-guided site-directed mutagenesis. The glucan phosphatase Like SEX4 2 from A. thaliana has two SBSs with weak affinity for β-cyclodextrin, amylose and amylopectin, which were indicated by mutational analysis to be more important than the active site for initial substrate recognition. The present review provides an update on occurrence of functional SBDs and SBSs in enzymes involved in starch biosynthesis.
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Affiliation(s)
- Casper Wilkens
- Enzyme Technology, Department of Bioengineering and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Birte Svensson
- Enzyme and Protein Chemistry, Department of Bioengineering and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Marie Sofie Møller
- Enzyme and Protein Chemistry, Department of Bioengineering and Biomedicine, Technical University of Denmark, Lyngby, Denmark
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17
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Skryhan K, Gurrieri L, Sparla F, Trost P, Blennow A. Redox Regulation of Starch Metabolism. FRONTIERS IN PLANT SCIENCE 2018; 9:1344. [PMID: 30298078 PMCID: PMC6160744 DOI: 10.3389/fpls.2018.01344] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/24/2018] [Indexed: 05/04/2023]
Abstract
Metabolism of starch is a major biological integrator of plant growth supporting nocturnal energy dynamics by transitory starch degradation as well as periods of dormancy, re-growth, and reproduction by utilization of storage starch. Especially, the extraordinarily well-tuned and coordinated rate of transient starch biosynthesis and degradation suggests the presence of very sophisticated regulatory mechanisms. Together with the circadian clock, land plants (being autotrophic and sessile organisms) need to monitor, sense, and recognize the photosynthetic rate, soil mineral availability as well as various abiotic and biotic stress factors. Currently it is widely accepted that post-translational modifications are the main way by which the diel periodic activity of enzymes of transient starch metabolism are regulated. Among these mechanisms, thiol-based redox regulation is suggested to be of fundamental importance and in chloroplasts, thioredoxins (Trx) are tightly linked up to photosynthesis and mediate light/dark regulation of metabolism. Also, light independent NADP-thioredoxin reductase C (NTRC) plays a major role in reactive oxygen species scavenging. Moreover, Trx and NTRC systems are interconnected at several levels and strongly influence each other. Most enzymes involved in starch metabolism are demonstrated to be redox-sensitive in vitro. However, to what extent their redox sensitivity is physiologically relevant in synchronizing starch metabolism with photosynthesis, heterotrophic energy demands, and oxidative protection is still unclear. For example, many hydrolases are activated under reducing (light) conditions and the strict separation between light and dark metabolic pathways is now challenged by data suggesting degradation of starch during the light period.
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Affiliation(s)
- Katsiaryna Skryhan
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Libero Gurrieri
- Department of Pharmacy and Biotechnology – FaBiT, University of Bologna, Bologna, Italy
| | - Francesca Sparla
- Department of Pharmacy and Biotechnology – FaBiT, University of Bologna, Bologna, Italy
| | - Paolo Trost
- Department of Pharmacy and Biotechnology – FaBiT, University of Bologna, Bologna, Italy
| | - Andreas Blennow
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- *Correspondence: Andreas Blennow,
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18
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Monroe JD, Breault JS, Pope LE, Torres CE, Gebrejesus TB, Berndsen CE, Storm AR. Arabidopsis β-Amylase2 Is a K +-Requiring, Catalytic Tetramer with Sigmoidal Kinetics. PLANT PHYSIOLOGY 2017; 175:1525-1535. [PMID: 29066669 PMCID: PMC5717748 DOI: 10.1104/pp.17.01506] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 05/11/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) genome contains nine β-amylase (BAM) genes, some of which play important roles in starch hydrolysis. However, little is known about BAM2, a plastid-localized enzyme reported to have extremely low catalytic activity. Using conservation of intron positions, we determined that the nine Arabidopsis BAM genes fall into two distinct subfamilies. A similar pattern was found in each major lineage of land plants, suggesting that these subfamilies diverged prior to the origin of land plants. Moreover, phylogenetic analysis indicated that BAM2 is the ancestral member of one of these subfamilies. This finding, along with the conservation of amino acids in the active site of BAM2, suggested that it might be catalytically active. We then identified KCl as necessary for BAM2 activity. Unlike BAM1, BAM3, and BAM5, three Arabidopsis BAMs that all exhibited hyperbolic kinetics, BAM2 exhibited sigmoidal kinetics with a Hill coefficient of over 3. Using multi-angle light scattering, we determined that BAM2 was a tetramer, whereas BAM5 was a monomer. Conserved residues from a diverse set of BAM2 orthologs were mapped onto a homology model of the protein, revealing a large, conserved surface away from the active site that we hypothesize is a secondary carbohydrate-binding site. Introduction of bulky methionine for glycine at two points on this surface reduced catalytic activity significantly without disrupting the tetrameric structure. Expression analysis indicated that BAM2 is more closely coexpressed with other starch degradation enzymes than any other BAM, suggesting that BAM2 may play an important role in starch degradation in plants.
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Affiliation(s)
- Jonathan D Monroe
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807
| | - Jillian S Breault
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807
| | - Lauren E Pope
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807
| | - Catherine E Torres
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807
| | | | - Christopher E Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807
| | - Amanda R Storm
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807
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19
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Taybi T, Cushman JC, Borland AM. Leaf carbohydrates influence transcriptional and post-transcriptional regulation of nocturnal carboxylation and starch degradation in the facultative CAM plant, Mesembryanthemum crystallinum. JOURNAL OF PLANT PHYSIOLOGY 2017; 218:144-154. [PMID: 28822907 DOI: 10.1016/j.jplph.2017.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/19/2017] [Accepted: 07/28/2017] [Indexed: 05/09/2023]
Abstract
Nocturnal degradation of transitory starch is a limiting factor for the optimal function of crassulacean acid metabolism and must be coordinated with phosphoenolypyruvate carboxylase (PEPC)-mediated CO2 uptake to optimise carbon gain over the diel cycle. The aim of this study was to test the hypothesis that nocturnal carboxylation is coordinated with starch degradation in CAM via a mechanism whereby the products of these pathways regulate diel transcript abundance and enzyme activities for both processes. To test this hypothesis, a starch and CAM-deficient mutant of Mesembryanthemum crystallinum was compared with wild type plants under well-watered and saline (CAM-inducing) conditions. Exposure to salinity increased the transcript abundance of genes required for nocturnal carboxylation, starch and sucrose degradation in both wild type and mutant, but the transcript abundance of several of these genes was not sustained over the dark period in the low-carbohydrate, CAM-deficient mutant. The diel pattern of transcript abundance for PEPC mirrored that of PEPC protein, as did the transcripts, protein, and activity of chloroplastic starch phosphorylase in both wild type and mutant, suggesting robust diel coordination of these metabolic processes. Activities of several amylase isoforms were low or lacking in the mutant, whilst the activity of a cytosolic isoform of starch phosphorylase was significantly elevated, indicating contrasting modes of metabolic regulation for the hydrolytic and phosphorylytic routes of starch degradation. Externally supplied sucrose resulted in an increase in nocturnal transcript abundance of genes required for nocturnal carboxylation and starch degradation. These results demonstrate that carbohydrates impact on transcriptional and post-transcriptional regulation of nocturnal carboxylation and starch degradation in CAM.
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Affiliation(s)
- Tahar Taybi
- School of Natural & Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, MS330, University of Nevada, Reno, NV 89557 USA
| | - Anne M Borland
- School of Natural & Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne NE1 7RU, UK; Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
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20
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Alpha-Glucan, Water Dikinase 1 Affects Starch Metabolism and Storage Root Growth in Cassava (Manihot esculenta Crantz). Sci Rep 2017; 7:9863. [PMID: 28852191 PMCID: PMC5575247 DOI: 10.1038/s41598-017-10594-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 08/10/2017] [Indexed: 11/20/2022] Open
Abstract
Regulation of storage root development by source strength remains largely unknown. The cassava storage root delay (srd) T-DNA mutant postpones storage root development but manifests normal foliage growth as wild-type plants. The SRD gene was identified as an orthologue of α-glucan, water dikinase 1 (GWD1), whose expression is regulated under conditions of light/dark cycles in leaves and is associated with storage root development. The GWD1-RNAi cassava plants showed both retarded plant and storage root growth, as a result of starch excess phenotypes with reduced photosynthetic capacity and decreased levels of soluble saccharides in their leaves. These leaves contained starch granules having greatly increased amylose content and type C semi-crystalline structures with increased short chains that suggested storage starch. In storage roots of GWD1-RNAi lines, maltose content was dramatically decreased and starches with much lower phosphorylation levels showed a drastically reduced β-amylolytic rate. These results suggested that GWD1 regulates transient starch morphogenesis and storage root growth by decreasing photo-assimilation partitioning from the source to the sink and by starch mobilization in root crops.
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21
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Fernandez O, Ishihara H, George GM, Mengin V, Flis A, Sumner D, Arrivault S, Feil R, Lunn JE, Zeeman SC, Smith AM, Stitt M. Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day. PLANT PHYSIOLOGY 2017; 174:2199-2212. [PMID: 28663333 PMCID: PMC5543966 DOI: 10.1104/pp.17.00601] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/24/2017] [Indexed: 05/17/2023]
Abstract
We investigated whether starch degradation occurs at the same time as starch synthesis in Arabidopsis (Arabidopsis thaliana) leaves in the light. Starch accumulated in a linear fashion for about 12 h after dawn, then accumulation slowed and content plateaued. Following decreases in light intensity, the rate of accumulation of starch declined in proportion to the decline in photosynthesis if the decrease occurred <10 h after dawn, but accumulation ceased or loss of starch occurred if the same decrease in light intensity was imposed more than 10 h after dawn. These changes in starch accumulation patterns after prolonged periods in the light occurred at both high and low starch contents and were not related to time-dependent changes in either the rate of photosynthesis or the partitioning of assimilate between starch and Suc, as assessed from metabolite measurements and 14CO2 pulse experiments. Instead, measurements of incorporation of 13C from 13CO2 into starch and of levels of the starch degradation product maltose showed that substantial starch degradation occurred simultaneously with synthesis at time points >14 h after dawn and in response to decreases in light intensity that occurred >10 h after dawn. Starch measurements in circadian clock mutants suggested that the clock influences the timing of onset of degradation. We conclude that the propensity for leaf starch to be degraded increases with time after dawn. The importance of this phenomenon for efficient use of carbon for growth in long days and for prevention of starvation during twilight is discussed.
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Affiliation(s)
- Olivier Fernandez
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Hirofumi Ishihara
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Gavin M George
- ETH Zürich, Plant Biochemistry, CH-8092 Zurich, Switzerland
| | - Virginie Mengin
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Anna Flis
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Dean Sumner
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Stéphanie Arrivault
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - Regina Feil
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | - John E Lunn
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
| | | | - Alison M Smith
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Mark Stitt
- Max Planck Institute for Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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22
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Pirone C, Gurrieri L, Gaiba I, Adamiano A, Valle F, Trost P, Sparla F. The analysis of the different functions of starch-phosphorylating enzymes during the development of Arabidopsis thaliana plants discloses an unexpected role for the cytosolic isoform GWD2. PHYSIOLOGIA PLANTARUM 2017; 160:447-457. [PMID: 28303594 DOI: 10.1111/ppl.12564] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 02/01/2017] [Accepted: 02/15/2017] [Indexed: 05/20/2023]
Abstract
The genome of Arabidopsis thaliana encodes three glucan, water dikinases. Glucan, water dikinase 1 (GWD1; EC 2.7.9.4) and phosphoglucan, water dikinase (PWD; EC 2.7.9.5) are chloroplastic enzymes, while glucan, water dikinase 2 (GWD2) is cytosolic. Both GWDs and PWD catalyze the addition of phosphate groups to amylopectin chains at the surface of starch granules, changing its physicochemical properties. As a result, GWD1 and PWD have a positive effect on transitory starch degradation at night. Because of its cytosolic localization, GWD2 does not have the same effect. Single T-DNA mutants of either GWD1 or PWD or GWD2 have been analyzed during the entire life cycle of A. thaliana. We report that the three dikinases are all important for proper seed development. Seeds from gwd2 mutants are shrunken, with the epidermal cells of the seed coat irregularly shaped. Moreover, gwd2 seeds contain a lower lipid to protein ratio and are impaired in germination. Similar seed phenotypes were observed in pwd and gwd1 mutants, except for the normal morphology of epidermal cells in gwd1 seed coats. The gwd1, pwd and gwd2 mutants were also very similar in growth and flowering time when grown under continuous light and all three behaved differently from wild-type plants. Besides pinpointing a novel role of GWD2 and PWD in seed development, this analysis suggests that the phenotypic features of the dikinase mutants in A. thaliana cannot be explained solely in terms of defects in leaf starch degradation at night.
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Affiliation(s)
- Claudia Pirone
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, 40126, Italy
| | - Libero Gurrieri
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, 40126, Italy
| | - Ivan Gaiba
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, 40126, Italy
| | - Alessio Adamiano
- Department of Chemistry "G. Ciamician", University of Bologna, Bologna, 40126, Italy
- Institute of Science and Technology for Ceramics (ISTEC), National Research Council (CNR), Faenza, 48018, Italy
| | - Francesco Valle
- Institute for the Study of Nanostructured Materials (ISNM), National Research Council (CNR), Bologna, 40129, Italy
| | - Paolo Trost
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, 40126, Italy
| | - Francesca Sparla
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Bologna, 40126, Italy
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23
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MacNeill GJ, Mehrpouyan S, Minow MAA, Patterson JA, Tetlow IJ, Emes MJ. Starch as a source, starch as a sink: the bifunctional role of starch in carbon allocation. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4433-4453. [PMID: 28981786 DOI: 10.1093/jxb/erx291] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Starch commands a central role in the carbon budget of the majority of plants on earth, and its biological role changes during development and in response to the environment. Throughout the life of a plant, starch plays a dual role in carbon allocation, acting as both a source, releasing carbon reserves in leaves for growth and development, and as a sink, either as a dedicated starch store in its own right (in seeds and tubers), or as a temporary reserve of carbon contributing to sink strength, in organs such as flowers, fruits, and developing non-starchy seeds. The presence of starch in tissues and organs thus has a profound impact on the physiology of the growing plant as its synthesis and degradation governs the availability of free sugars, which in turn control various growth and developmental processes. This review attempts to summarize the large body of information currently available on starch metabolism and its relationship to wider aspects of carbon metabolism and plant nutrition. It highlights gaps in our knowledge and points to research areas that show promise for bioengineering and manipulation of starch metabolism in order to achieve more desirable phenotypes such as increased yield or plant biomass.
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Affiliation(s)
- Gregory J MacNeill
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Sahar Mehrpouyan
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Mark A A Minow
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Jenelle A Patterson
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Ian J Tetlow
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Michael J Emes
- Department of Molecular and Cellular Biology, College of Biological Science, Summerlee Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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24
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Highly phosphorylated functionalized rice starch produced by transgenic rice expressing the potato GWD1 gene. Sci Rep 2017; 7:3339. [PMID: 28611462 PMCID: PMC5469863 DOI: 10.1038/s41598-017-03637-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/02/2017] [Indexed: 11/20/2022] Open
Abstract
Starch phosphorylation occurs naturally during starch metabolism in the plant and is catalysed by glucan water dikinases (GWD1) and phosphoglucan water dikinase/glucan water dikinase 3 (PWD/GWD3). We generated six stable individual transgenic lines by over-expressing the potato GWD1 in rice. Transgenic rice grain starch had 9-fold higher 6-phospho (6-P) monoesters and double amounts of 3-phospho (3-P) monoesters, respectively, compared to control grain. The shape and topography of the transgenic starch granules were moderately altered including surface pores and less well defined edges. The gelatinization temperatures of both rice flour and extracted starch were significantly lower than those of the control and hence negatively correlated with the starch phosphate content. The 6-P content was positively correlated with amylose content and relatively long amylopectin chains with DP25-36, and the 3-P content was positively correlated with short chains of DP6-12. The starch pasting temperature, peak viscosity and the breakdown were lower but the setback was higher for transgenic rice flour. The 6-P content was negatively correlated with texture adhesiveness but positively correlated with the cohesiveness of rice flour gels. Our data demonstrate a way forward to employ a starch bioengineering approach for clean modification of starch, opening up completely new applications for rice starch.
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25
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Santelia D, Lunn JE. Transitory Starch Metabolism in Guard Cells: Unique Features for a Unique Function. PLANT PHYSIOLOGY 2017; 174:539-549. [PMID: 28292855 PMCID: PMC5462065 DOI: 10.1104/pp.17.00211] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/10/2017] [Indexed: 05/18/2023]
Abstract
The pathway and timing of starch turnover in guard cells differs from mesophyll cells and is linked to stomatal opening in the light.
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Affiliation(s)
- Diana Santelia
- Department of Plant and Microbial Biology, University of Zürich, CH-8008 Zürich, Switzerland (D.S.); and
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany (J.E.L.)
| | - John E Lunn
- Department of Plant and Microbial Biology, University of Zürich, CH-8008 Zürich, Switzerland (D.S.); and
- Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany (J.E.L.)
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26
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Li J, Wu L, Foster R, Ruan YL. Molecular regulation of sucrose catabolism and sugar transport for development, defence and phloem function. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:322-335. [PMID: 28304127 DOI: 10.1111/jipb.12539] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 03/15/2017] [Indexed: 06/06/2023]
Abstract
Sucrose (Suc) is the major end product of photosynthesis in mesophyll cells of most vascular plants. It is loaded into phloem of mature leaves for long-distance translocation to non-photosynthetic organs where it is unloaded for diverse uses. Clearly, Suc transport and metabolism is central to plant growth and development and the functionality of the entire vascular system. Despite vast information in the literature about the physiological roles of individual sugar metabolic enzymes and transporters, there is a lack of systematic evaluation about their molecular regulation from transcriptional to post-translational levels. Knowledge on this topic is essential for understanding and improving plant development, optimizing resource distribution and increasing crop productivity. We therefore focused our analyses on molecular control of key players in Suc metabolism and transport, including: (i) the identification of promoter elements responsive to sugars and hormones or targeted by transcription factors and microRNAs degrading transcripts of target genes; and (ii) modulation of enzyme and transporter activities through protein-protein interactions and other post-translational modifications. We have highlighted major remaining questions and discussed opportunities to exploit current understanding to gain new insights into molecular control of carbon partitioning for improving plant performance.
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Affiliation(s)
- Jun Li
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Australia
| | - Limin Wu
- CSIRO Agriculture, Canberra, ACT 2601, Australia
| | - Ryan Foster
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Australia
| | - Yong-Ling Ruan
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Australia
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27
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Mora-García S, de Leone MJ, Yanovsky M. Time to grow: circadian regulation of growth and metabolism in photosynthetic organisms. CURRENT OPINION IN PLANT BIOLOGY 2017; 35:84-90. [PMID: 27912128 DOI: 10.1016/j.pbi.2016.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/10/2016] [Accepted: 11/11/2016] [Indexed: 05/21/2023]
Abstract
Circadian clocks are molecular devices that help adjust organisms to periodic environmental changes. Although formally described as self-sustaining oscillators that are synchronized by external cues and produce defined outputs, it is increasingly clear that physiological processes not only are regulated by, but also regulate the function of the clock. We discuss three recent examples of the intimate relationships between the function of the clock, growth and metabolism in photosynthetic organisms: the daily tracking of sun by sunflowers, the fine computations plants and cyanobacteria perform to manage carbon reserves and prevent starvation, and the changes in clock parameters that went along with domestication of tomato.
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Affiliation(s)
- Santiago Mora-García
- Fundación Instituto Leloir, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina.
| | - María José de Leone
- Fundación Instituto Leloir, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina
| | - Marcelo Yanovsky
- Fundación Instituto Leloir, Av. Patricias Argentinas 435, 1405 Buenos Aires, Argentina.
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28
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Duitama J, Kafuri L, Tello D, Leiva AM, Hofinger B, Datta S, Lentini Z, Aranzales E, Till B, Ceballos H. Deep Assessment of Genomic Diversity in Cassava for Herbicide Tolerance and Starch Biosynthesis. Comput Struct Biotechnol J 2017; 15:185-194. [PMID: 28179981 PMCID: PMC5295625 DOI: 10.1016/j.csbj.2017.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/26/2016] [Accepted: 01/10/2017] [Indexed: 12/16/2022] Open
Abstract
Cassava is one of the most important food security crops in tropical countries, and a competitive resource for the starch, food, feed and ethanol industries. However, genomics research in this crop is much less developed compared to other economically important crops such as rice or maize. The International Center for Tropical Agriculture (CIAT) maintains the largest cassava germplasm collection in the world. Unfortunately, the genetic potential of this diversity for breeding programs remains underexploited due to the difficulties in phenotypic screening and lack of deep genomic information about the different accessions. A chromosome-level assembly of the cassava reference genome was released this year and only a handful of studies have been made, mainly to find quantitative trait loci (QTL) on breeding populations with limited variability. This work presents the results of pooled targeted resequencing of more than 1500 cassava accessions from the CIAT germplasm collection to obtain a dataset of more than 2000 variants within genes related to starch functional properties and herbicide tolerance. Results of twelve bioinformatic pipelines for variant detection in pooled samples were compared to ensure the quality of the variant calling process. Predictions of functional impact were performed using two separate methods to prioritize interesting variation for genotyping and cultivar selection. Targeted resequencing, either by pooled samples or by similar approaches such as Ecotilling or capture, emerges as a cost effective alternative to whole genome sequencing to identify interesting alleles of genes related to relevant traits within large germplasm collections.
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Affiliation(s)
- Jorge Duitama
- Agrobiodiversity Research Area, International Center for Tropical Agriculture (CIAT), Cali, Colombia
- Systems and Computing Engineering Department, Universidad de los Andes, Bogotá, Colombia
| | - Lina Kafuri
- Plant Breeding and Genetics Laboratory, Joint FAO/IAEA Division, International Atomic Energy Agency, Seibersdorf, Austria
- Department of Biological Sciences, School of Natural Sciences, Universidad Icesi, Cali, Colombia
| | - Daniel Tello
- Plant Breeding and Genetics Laboratory, Joint FAO/IAEA Division, International Atomic Energy Agency, Seibersdorf, Austria
- Department of Biological Sciences, School of Natural Sciences, Universidad Icesi, Cali, Colombia
| | - Ana María Leiva
- Agrobiodiversity Research Area, International Center for Tropical Agriculture (CIAT), Cali, Colombia
| | - Bernhard Hofinger
- Plant Breeding and Genetics Laboratory, Joint FAO/IAEA Division, International Atomic Energy Agency, Seibersdorf, Austria
| | - Sneha Datta
- Plant Breeding and Genetics Laboratory, Joint FAO/IAEA Division, International Atomic Energy Agency, Seibersdorf, Austria
| | - Zaida Lentini
- Department of Biological Sciences, School of Natural Sciences, Universidad Icesi, Cali, Colombia
| | - Ericson Aranzales
- Agrobiodiversity Research Area, International Center for Tropical Agriculture (CIAT), Cali, Colombia
| | - Bradley Till
- Plant Breeding and Genetics Laboratory, Joint FAO/IAEA Division, International Atomic Energy Agency, Seibersdorf, Austria
| | - Hernán Ceballos
- Agrobiodiversity Research Area, International Center for Tropical Agriculture (CIAT), Cali, Colombia
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29
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Jones MA. Interplay of Circadian Rhythms and Light in the Regulation of Photosynthesis-Derived Metabolism. PROGRESS IN BOTANY VOL. 79 2017:147-171. [PMID: 0 DOI: 10.1007/124_2017_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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30
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Characterization of Starch Degradation Related Genes in Postharvest Kiwifruit. Int J Mol Sci 2016; 17:ijms17122112. [PMID: 27983700 PMCID: PMC5187912 DOI: 10.3390/ijms17122112] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/05/2016] [Accepted: 12/13/2016] [Indexed: 11/16/2022] Open
Abstract
Starch is one of the most important storage carbohydrates in plants. Kiwifruit typically accumulate large amounts of starch during development. The fruit retain starch until commercial maturity, and its postharvest degradation is essential for consumer acceptance. The activity of genes related to starch degradation has, however, rarely been investigated. Based on the kiwifruit genome sequence and previously reported starch degradation-related genes, 17 novel genes were isolated and the relationship between their expression and starch degradation was examined using two sets of materials: ethylene-treated (100 µL/L, 20 °C; ETH) vs. control (20 °C; CK) and controlled atmosphere stored (CA, 5% CO2 + 2% O2, 0 °C) vs. normal atmosphere in cold storage (NA, 0 °C). Physiological analysis indicated that ETH accelerated starch degradation and increased soluble solids content (SSC) and soluble sugars (glucose, fructose and sucrose), while CA inhibited starch reduction compared with NA. Using these materials, expression patterns of 24 genes that may contribute to starch degradation (seven previously reported and 17 newly isolated) were analyzed. Among the 24 genes, AdAMY1, AdAGL3 and AdBAM3.1/3L/9 were significantly induced by ETH and positively correlated with starch degradation. Furthermore, these five genes were also inhibited by CA, conforming the likely involvement of these genes in starch degradation. Thus, the present study has identified the genes with potential for involvement in starch degradation in postharvest kiwifruit, which will be useful for understanding the regulation of kiwifruit starch content and metabolism.
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31
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Xu X, Dees D, Dechesne A, Huang XF, Visser RGF, Trindade LM. Starch phosphorylation plays an important role in starch biosynthesis. Carbohydr Polym 2016; 157:1628-1637. [PMID: 27987877 DOI: 10.1016/j.carbpol.2016.11.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 10/20/2022]
Abstract
Starch phosphate esters are crucial in starch metabolism and render valuable functionality to starches for various industrial applications. A potato glucan, water dikinase (GWD1) was introduced in tubers of two different potato genetic backgrounds: an amylose-containing line Kardal and the amylose-free mutant amf. In both backgrounds, this resulted in two contrasting effects, a number of plants showed higher phosphate content compared to the respective control, while others lines exhibited lower phosphate content, thereby generating two series of starches with broad-scale variation in phosphate content. The results of systematic analyses on these two series of starches revealed that starch phosphate content strongly influenced starch granule morphology, amylose content, starch fine structure, gelatinization characteristics and freeze-thaw stability of starch gels. Further analyses on the expression level of genes involved in starch metabolism suggested that starch phosphorylation regulates starch synthesis by controlling the carbon flux into starch while simultaneously modulating starch-synthesizing genes.
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Affiliation(s)
- Xuan Xu
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands; National Centre for Vegetable Improvement (Central China), Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China.
| | - Dianka Dees
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
| | - Annemarie Dechesne
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
| | - Xing-Feng Huang
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
| | - Richard G F Visser
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
| | - Luisa M Trindade
- Wageningen UR Plant Breeding, Wageningen University and Research, P.O. Box 386, 6700 AJ Wageningen, The Netherlands.
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32
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Verbeke J, Penverne C, D’Hulst C, Rolando C, Szydlowski N. Rapid and sensitive quantification of C3- and C6-phosphoesters in starch by fluorescence-assisted capillary electrophoresis. Carbohydr Polym 2016; 152:784-791. [DOI: 10.1016/j.carbpol.2016.07.057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/13/2016] [Accepted: 07/16/2016] [Indexed: 11/25/2022]
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33
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Shibata A, Takahashi F, Kasahara M, Imamura N. Induction of Maltose Release by Light in the Endosymbiont Chlorella variabilis of Paramecium bursaria. Protist 2016; 167:468-478. [DOI: 10.1016/j.protis.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 08/17/2016] [Accepted: 08/25/2016] [Indexed: 11/24/2022]
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34
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Flis A, Sulpice R, Seaton DD, Ivakov AA, Liput M, Abel C, Millar AJ, Stitt M. Photoperiod-dependent changes in the phase of core clock transcripts and global transcriptional outputs at dawn and dusk in Arabidopsis. PLANT, CELL & ENVIRONMENT 2016; 39:1955-81. [PMID: 27075884 DOI: 10.1111/pce.12754] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 04/01/2016] [Indexed: 05/06/2023]
Abstract
Plants use the circadian clock to sense photoperiod length. Seasonal responses like flowering are triggered at a critical photoperiod when a light-sensitive clock output coincides with light or darkness. However, many metabolic processes, like starch turnover, and growth respond progressively to photoperiod duration. We first tested the photoperiod response of 10 core clock genes and two output genes. qRT-PCR analyses of transcript abundance under 6, 8, 12 and 18 h photoperiods revealed 1-4 h earlier peak times under short photoperiods and detailed changes like rising PRR7 expression before dawn. Clock models recapitulated most of these changes. We explored the consequences for global gene expression by performing transcript profiling in 4, 6, 8, 12 and 18 h photoperiods. There were major changes in transcript abundance at dawn, which were as large as those between dawn and dusk in a given photoperiod. Contributing factors included altered timing of the clock relative to dawn, light signalling and changes in carbon availability at night as a result of clock-dependent regulation of starch degradation. Their interaction facilitates coordinated transcriptional regulation of key processes like starch turnover, anthocyanin, flavonoid and glucosinolate biosynthesis and protein synthesis and underpins the response of metabolism and growth to photoperiod.
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Affiliation(s)
- Anna Flis
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, GPO Box 475, Canberra, Australian Capital Territory, 2601, Australia
| | - Ronan Sulpice
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
- Plant Systems Biology Lab, Plant and AgriBiosciences Research Centre, Botany and Plant Science, NUIG, Galway, Ireland
| | - Daniel D Seaton
- SynthSys and School of Biological Sciences, C.H. Waddington Building, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Alexander A Ivakov
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, GPO Box 475, Canberra, Australian Capital Territory, 2601, Australia
| | - Magda Liput
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
| | - Christin Abel
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
| | - Andrew J Millar
- SynthSys and School of Biological Sciences, C.H. Waddington Building, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14476, Golm, Potsdam, Germany
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35
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Abstract
Starch-rich crops form the basis of our nutrition, but plants have still to yield all their secrets as to how they make this vital substance. Great progress has been made by studying both crop and model systems, and we approach the point of knowing the enzymatic machinery responsible for creating the massive, insoluble starch granules found in plant tissues. Here, we summarize our current understanding of these biosynthetic enzymes, highlighting recent progress in elucidating their specific functions. Yet, in many ways we have only scratched the surface: much uncertainty remains about how these components function together and are controlled. We flag-up recent observations suggesting a significant degree of flexibility during the synthesis of starch and that previously unsuspected non-enzymatic proteins may have a role. We conclude that starch research is not yet a mature subject and that novel experimental and theoretical approaches will be important to advance the field.
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Affiliation(s)
- Barbara Pfister
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Samuel C Zeeman
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland.
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36
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Emanuelle S, Brewer MK, Meekins DA, Gentry MS. Unique carbohydrate binding platforms employed by the glucan phosphatases. Cell Mol Life Sci 2016; 73:2765-2778. [PMID: 27147465 PMCID: PMC4920694 DOI: 10.1007/s00018-016-2249-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 12/19/2022]
Abstract
Glucan phosphatases are a family of enzymes that are functionally conserved at the enzymatic level in animals and plants. These enzymes bind and dephosphorylate glycogen in animals and starch in plants. While the enzymatic function is conserved, the glucan phosphatases employ distinct mechanisms to bind and dephosphorylate glycogen or starch. The founding member of the family is a bimodular human protein called laforin that is comprised of a carbohydrate binding module 20 (CBM20) followed by a dual specificity phosphatase domain. Plants contain two glucan phosphatases: Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2). SEX4 contains a chloroplast targeting peptide, dual specificity phosphatase (DSP) domain, a CBM45, and a carboxy-terminal motif. LSF2 is comprised of simply a chloroplast targeting peptide, DSP domain, and carboxy-terminal motif. SEX4 employs an integrated DSP-CBM glucan-binding platform to engage and dephosphorylate starch. LSF2 lacks a CBM and instead utilizes two surface binding sites to bind and dephosphorylate starch. Laforin is a dimeric protein in solution and it utilizes a tetramodular architecture and cooperativity to bind and dephosphorylate glycogen. This chapter describes the biological role of glucan phosphatases in glycogen and starch metabolism and compares and contrasts their ability to bind and dephosphorylate glucans.
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Affiliation(s)
- Shane Emanuelle
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536 USA
| | - M. Kathryn Brewer
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536 USA
| | - David A. Meekins
- Division of Biology, Kansas State University, Manhattan, KS 66506 USA
| | - Matthew S. Gentry
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536 USA
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37
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Boyer L, Roussel X, Courseaux A, Ndjindji OM, Lancelon-Pin C, Putaux JL, Tetlow IJ, Emes MJ, Pontoire B, D' Hulst C, Wattebled F. Expression of Escherichia coli glycogen branching enzyme in an Arabidopsis mutant devoid of endogenous starch branching enzymes induces the synthesis of starch-like polyglucans. PLANT, CELL & ENVIRONMENT 2016; 39:1432-1447. [PMID: 26715025 DOI: 10.1111/pce.12702] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 12/08/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
Starch synthesis requires several enzymatic activities including branching enzymes (BEs) responsible for the formation of α(1 → 6) linkages. Distribution and number of these linkages are further controlled by debranching enzymes that cleave some of them, rendering the polyglucan water-insoluble and semi-crystalline. Although the activity of BEs and debranching enzymes is mandatory to sustain normal starch synthesis, the relative importance of each in the establishment of the plant storage polyglucan (i.e. water insolubility, crystallinity and presence of amylose) is still debated. Here, we have substituted the activity of BEs in Arabidopsis with that of the Escherichia coli glycogen BE (GlgB). The latter is the BE counterpart in the metabolism of glycogen, a highly branched water-soluble and amorphous storage polyglucan. GlgB was expressed in the be2 be3 double mutant of Arabidopsis, which is devoid of BE activity and consequently free of starch. The synthesis of a water-insoluble, partly crystalline, amylose-containing starch-like polyglucan was restored in GlgB-expressing plants, suggesting that BEs' origin only has a limited impact on establishing essential characteristics of starch. Moreover, the balance between branching and debranching is crucial for the synthesis of starch, as an excess of branching activity results in the formation of highly branched, water-soluble, poorly crystalline polyglucan.
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Affiliation(s)
- Laura Boyer
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Xavier Roussel
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Adeline Courseaux
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Ofilia M Ndjindji
- Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000, Grenoble, France
- CNRS, CERMAV, F-38000, Grenoble, France
| | - Christine Lancelon-Pin
- Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000, Grenoble, France
- CNRS, CERMAV, F-38000, Grenoble, France
| | - Jean-Luc Putaux
- Université Grenoble Alpes, Centre de Recherches sur les Macromolécules Végétales (CERMAV), F-38000, Grenoble, France
- CNRS, CERMAV, F-38000, Grenoble, France
| | - Ian J Tetlow
- Department of Molecular and Cellular Biology, Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Michael J Emes
- Department of Molecular and Cellular Biology, Science Complex, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | | | - Christophe D' Hulst
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
| | - Fabrice Wattebled
- Univ. Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000, Lille, France
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Mahlow S, Orzechowski S, Fettke J. Starch phosphorylation: insights and perspectives. Cell Mol Life Sci 2016; 73:2753-64. [PMID: 27147464 PMCID: PMC11108486 DOI: 10.1007/s00018-016-2248-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 01/12/2023]
Abstract
During starch metabolism, the phosphorylation of glucosyl residues of starch, to be more precise of amylopectin, is a repeatedly observed process. This phosphorylation is mediated by dikinases, the glucan, water dikinase (GWD) and the phosphoglucan, water dikinase (PWD). The starch-related dikinases utilize ATP as dual phosphate donor transferring the terminal γ-phosphate group to water and the β-phosphate group selectively to either C6 position or C3 position of a glucosyl residue within amylopectin. By the collaborative action of both enzymes, the initiation of a transition of α-glucans from highly ordered, water-insoluble state to a less order state is realized and thus the initial process of starch degradation. Consequently, mutants lacking either GWD or PWD reveal a starch excess phenotype as well as growth retardation. In this review, we focus on the increased knowledge collected over the last years related to enzymatic properties, the precise definition of the substrates, the physiological implications, and discuss ongoing questions.
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Affiliation(s)
- Sebastian Mahlow
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany
- Institute of General Botany, Friedrich Schiller University Jena, Am Planetarium 1, 07743, Jena, Germany
| | - Sławomir Orzechowski
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany
- Department of Biochemistry, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Joerg Fettke
- Biopolymer Analytics, University of Potsdam, Karl-Liebknecht 24-25, 14476, Potsdam-Golm, Germany.
- Department of Biochemistry, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland.
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Feike D, Seung D, Graf A, Bischof S, Ellick T, Coiro M, Soyk S, Eicke S, Mettler-Altmann T, Lu KJ, Trick M, Zeeman SC, Smith AM. The Starch Granule-Associated Protein EARLY STARVATION1 Is Required for the Control of Starch Degradation in Arabidopsis thaliana Leaves. THE PLANT CELL 2016; 28:1472-89. [PMID: 27207856 PMCID: PMC4944407 DOI: 10.1105/tpc.16.00011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 04/29/2016] [Accepted: 05/17/2016] [Indexed: 05/18/2023]
Abstract
To uncover components of the mechanism that adjusts the rate of leaf starch degradation to the length of the night, we devised a screen for mutant Arabidopsis thaliana plants in which starch reserves are prematurely exhausted. The mutation in one such mutant, named early starvation1 (esv1), eliminates a previously uncharacterized protein. Starch in mutant leaves is degraded rapidly and in a nonlinear fashion, so that reserves are exhausted 2 h prior to dawn. The ESV1 protein and a similar uncharacterized Arabidopsis protein (named Like ESV1 [LESV]) are located in the chloroplast stroma and are also bound into starch granules. The region of highest similarity between the two proteins contains a series of near-repeated motifs rich in tryptophan. Both proteins are conserved throughout starch-synthesizing organisms, from angiosperms and monocots to green algae. Analysis of transgenic plants lacking or overexpressing ESV1 or LESV, and of double mutants lacking ESV1 and another protein necessary for starch degradation, leads us to propose that these proteins function in the organization of the starch granule matrix. We argue that their misexpression affects starch degradation indirectly, by altering matrix organization and, thus, accessibility of starch polymers to starch-degrading enzymes.
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Affiliation(s)
- Doreen Feike
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - David Seung
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Alexander Graf
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Sylvain Bischof
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Tamaryn Ellick
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Mario Coiro
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Sebastian Soyk
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Simona Eicke
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Tabea Mettler-Altmann
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Kuan Jen Lu
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Martin Trick
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Samuel C Zeeman
- Department of Biology, Eidgenössische Technische Hochschule Zürich, CH-8092 Zürich, Switzerland
| | - Alison M Smith
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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Ma J, Gao S, Jiang QT, Yang Q, Sun M, Wang JR, Qi PF, Liu YX, Li W, Pu ZE, Lan XJ, Wei YM, Liu C, Zheng YL. Structure and expression of phosphoglucan phosphatase genes of Like Sex Four1 and Like Sex Four2 in barley. Genetica 2016; 144:313-23. [PMID: 27154345 DOI: 10.1007/s10709-016-9900-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 04/27/2016] [Indexed: 10/21/2022]
Abstract
Phosphoglucan phosphatases (Like-SEX4 1 and 2; LSF1 and LSF2) were reported to play roles in starch metabolism in leaves of Arabidopsis. In this study, we identified and mapped the LSF1 and LSF2 genes in barley (HvLSF1 and HvLSF2), characterized their gene and protein structures, predicted the cis-elements of their promoters, and analysed their expression patterns. HvLSF1 and HvLSF2 were mapped on the long arm of chromosome 1H (1HL) and 5H (5HL), respectively. Our results revealed varied exon-intron structures and conserved exon-intron junctions in both LSF1 and LSF2 from a range of analysed species. Alignment of protein sequences indicated that cTP and CT domains are much less varied than the functional domains (PDZ, DPS and CBM48). LSF2 was mainly expressed in anthers of barley and rice, and in leaf of Arabidopsis. LSF1 was mainly expressed in endosperm of barley and leaf of Arabidopsis and rice. The expression of LSF1 exhibited a diurnal pattern in rice only and that of LSF2 in both rice and Arabidopsis. Of the investigated stresses, only cold stress significantly reduced expression level of LSF1 and LSF2 in barley and LSF2 in Arabidopsis at late stages of the treatments. While heat treatment significantly decreased expression levels of LSF1 at middle stage (4 h) of a treatment in Arabidopsis only. The strong relationships detected between LSF2 and starch excess4 (SEX4), glucan, water dikinases or phosphoglucan, water dikinases were identified and discussed. Taken together, these results provide information of genetic manipulation of LSF1 and LSF2, especially in monocotyledon and further elucidate their regulatory mechanism in plant development.
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Affiliation(s)
- Jian Ma
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Shang Gao
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Qian-Tao Jiang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
| | - Qiang Yang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Min Sun
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Ji-Rui Wang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Peng-Fei Qi
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Ya-Xi Liu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Wei Li
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Zhi-En Pu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Xiu-Jin Lan
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Yu-Ming Wei
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China
| | - Chunji Liu
- CSIRO Agriculture Flagship, 306 Carmody Road, St Lucia, Brisbane, QLD, 4067, Australia
| | - You-Liang Zheng
- Key Laboratory of Southwestern Crop Germplasm Utilization, Ministry of Agriculture, Sichuan Agricultural University, Ya'an, 625014, Sichuan, China.
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41
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Meekins DA, Vander Kooi CW, Gentry MS. Structural mechanisms of plant glucan phosphatases in starch metabolism. FEBS J 2016; 283:2427-47. [PMID: 26934589 DOI: 10.1111/febs.13703] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 01/31/2016] [Accepted: 02/29/2016] [Indexed: 01/12/2023]
Abstract
Glucan phosphatases are a recently discovered class of enzymes that dephosphorylate starch and glycogen, thereby regulating energy metabolism. Plant genomes encode two glucan phosphatases, called Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), that regulate starch metabolism by selectively dephosphorylating glucose moieties within starch glucan chains. Recently, the structures of both SEX4 and LSF2 were determined, with and without phosphoglucan products bound, revealing the mechanism for their unique activities. This review explores the structural and enzymatic features of the plant glucan phosphatases, and outlines how they are uniquely adapted to perform their cellular functions. We outline the physical mechanisms used by SEX4 and LSF2 to interact with starch glucans: SEX4 binds glucan chains via a continuous glucan-binding platform comprising its dual-specificity phosphatase domain and carbohydrate-binding module, while LSF2 utilizes surface binding sites. SEX4 and LSF2 both contain a unique network of aromatic residues in their catalytic dual-specificity phosphatase domains that serve as glucan engagement platforms and are unique to the glucan phosphatases. We also discuss the phosphoglucan substrate specificities inherent to SEX4 and LSF2, and outline structural features within the active site that govern glucan orientation. This review defines the structural mechanism of the plant glucan phosphatases with respect to phosphatases, starch metabolism and protein-glucan interaction, thereby providing a framework for their application in both agricultural and industrial settings.
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Affiliation(s)
- David A Meekins
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY, USA.,Division of Biology, Kansas State University, Manhattan, KS, USA
| | - Craig W Vander Kooi
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY, USA
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42
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Liu F, Zhao Q, Mano N, Ahmed Z, Nitschke F, Cai Y, Chapman KD, Steup M, Tetlow IJ, Emes MJ. Modification of starch metabolism in transgenic Arabidopsis thaliana increases plant biomass and triples oilseed production. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:976-985. [PMID: 26285603 DOI: 10.1111/pbi.12453] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/25/2015] [Accepted: 06/27/2015] [Indexed: 06/04/2023]
Abstract
We have identified a novel means to achieve substantially increased vegetative biomass and oilseed production in the model plant Arabidopsis thaliana. Endogenous isoforms of starch branching enzyme (SBE) were substituted by either one of the endosperm-expressed maize (Zea mays L.) branching isozymes, ZmSBEI or ZmSBEIIb. Transformants were compared with the starch-free background and with the wild-type plants. Each of the maize-derived SBEs restored starch biosynthesis but both morphology and structure of starch particles were altered. Altered starch metabolism in the transformants is associated with enhanced biomass formation and more-than-trebled oilseed production while maintaining seed oil quality. Enhanced oilseed production is primarily due to an increased number of siliques per plant whereas oil content and seed number per silique are essentially unchanged or even modestly decreased. Introduction of cereal starch branching isozymes into oilseed plants represents a potentially useful strategy to increase biomass and oilseed production in related crops and manipulate the structure and properties of leaf starch.
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Affiliation(s)
- Fushan Liu
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Qianru Zhao
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Noel Mano
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Zaheer Ahmed
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Felix Nitschke
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Yinqqi Cai
- Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, TX, USA
| | - Kent D Chapman
- Department of Biological Sciences, Center for Plant Lipid Research, University of North Texas, Denton, TX, USA
| | - Martin Steup
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Ian J Tetlow
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
| | - Michael J Emes
- Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, Guelph, ON, Canada
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43
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Starch Granule Re-Structuring by Starch Branching Enzyme and Glucan Water Dikinase Modulation Affects Caryopsis Physiology and Metabolism. PLoS One 2016; 11:e0149613. [PMID: 26891365 PMCID: PMC4758647 DOI: 10.1371/journal.pone.0149613] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/03/2016] [Indexed: 12/31/2022] Open
Abstract
Starch is of fundamental importance for plant development and reproduction and its optimized molecular assembly is potentially necessary for correct starch metabolism. Re-structuring of starch granules in-planta can therefore potentially affect plant metabolism. Modulation of granule micro-structure was achieved by decreasing starch branching and increasing starch-bound phosphate content in the barley caryopsis starch by RNAi suppression of all three Starch Branching Enzyme (SBE) isoforms or overexpression of potato Glucan Water Dikinase (GWD). The resulting lines displayed Amylose-Only (AO) and Hyper-Phosphorylated (HP) starch chemotypes, respectively. We studied the influence of these alterations on primary metabolism, grain composition, starch structural features and starch granule morphology over caryopsis development at 10, 20 and 30 days after pollination (DAP) and at grain maturity. While HP showed relatively little effect, AO showed significant reduction in starch accumulation with re-direction to protein and β-glucan (BG) accumulation. Metabolite profiling indicated significantly higher sugar accumulation in AO, with re-partitioning of carbon to accumulate amino acids, and interestingly it also had high levels of some important stress-related metabolites and potentially protective metabolites, possibly to elude deleterious effects. Investigations on starch molecular structure revealed significant increase in starch phosphate and amylose content in HP and AO respectively with obvious differences in starch granule morphology at maturity. The results demonstrate that decreasing the storage starch branching resulted in metabolic adjustments and re-directions, tuning to evade deleterious effects on caryopsis physiology and plant performance while only little effect was evident by increasing starch-bound phosphate as a result of overexpressing GWD.
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44
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Cuesta-Seijo JA, Nielsen MM, Ruzanski C, Krucewicz K, Beeren SR, Rydhal MG, Yoshimura Y, Striebeck A, Motawia MS, Willats WGT, Palcic MM. In vitro Biochemical Characterization of All Barley Endosperm Starch Synthases. FRONTIERS IN PLANT SCIENCE 2016; 6:1265. [PMID: 26858729 PMCID: PMC4730117 DOI: 10.3389/fpls.2015.01265] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/27/2015] [Indexed: 05/18/2023]
Abstract
Starch is the main storage polysaccharide in cereals and the major source of calories in the human diet. It is synthesized by a panel of enzymes including five classes of starch synthases (SSs). While the overall starch synthase (SS) reaction is known, the functional differences between the five SS classes are poorly understood. Much of our knowledge comes from analyzing mutant plants with altered SS activities, but the resulting data are often difficult to interpret as a result of pleitropic effects, competition between enzymes, overlaps in enzyme activity and disruption of multi-enzyme complexes. Here we provide a detailed biochemical study of the activity of all five classes of SSs in barley endosperm. Each enzyme was produced recombinantly in E. coli and the properties and modes of action in vitro were studied in isolation from other SSs and other substrate modifying activities. Our results define the mode of action of each SS class in unprecedented detail; we analyze their substrate selection, temperature dependence and stability, substrate affinity and temporal abundance during barley development. Our results are at variance with some generally accepted ideas about starch biosynthesis and might lead to the reinterpretation of results obtained in planta. In particular, they indicate that granule bound SS is capable of processive action even in the absence of a starch matrix, that SSI has no elongation limit, and that SSIV, believed to be critical for the initiation of starch granules, has maltoligosaccharides and not polysaccharides as its preferred substrates.
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Affiliation(s)
| | | | | | | | | | - Maja G. Rydhal
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
| | | | | | - Mohammed S. Motawia
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
| | - William G. T. Willats
- Department of Plant and Environmental Sciences, University of CopenhagenFrederiksberg, Copenhagen, Denmark
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45
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Bowerman AF, Newberry M, Dielen AS, Whan A, Larroque O, Pritchard J, Gubler F, Howitt CA, Pogson BJ, Morell MK, Ral JP. Suppression of glucan, water dikinase in the endosperm alters wheat grain properties, germination and coleoptile growth. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:398-408. [PMID: 25989474 DOI: 10.1111/pbi.12394] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 03/25/2015] [Accepted: 04/06/2015] [Indexed: 05/13/2023]
Abstract
Starch phosphate ester content is known to alter the physicochemical properties of starch, including its susceptibility to degradation. Previous work producing wheat (Triticum aestivum) with down-regulated glucan, water dikinase, the primary gene responsible for addition of phosphate groups to starch, in a grain-specific manner found unexpected phenotypic alteration in grain and growth. Here, we report on further characterization of these lines focussing on mature grain and early growth. We find that coleoptile length has been increased in these transgenic lines independently of grain size increases. No changes in starch degradation rates during germination could be identified, or any major alteration in soluble sugar levels that may explain the coleoptile growth modification. We identify some alteration in hormones in the tissues in question. Mature grain size is examined, as is Hardness Index and starch conformation. We find no evidence that the increased growth of coleoptiles in these lines is connected to starch conformation or degradation or soluble sugar content and suggest these findings provide a novel means of increasing coleoptile growth and early seedling establishment in cereal crop species.
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Affiliation(s)
- Andrew F Bowerman
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
- ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, ACT, Australia
| | - Marcus Newberry
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Anne-Sophie Dielen
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Alex Whan
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Oscar Larroque
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Jenifer Pritchard
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Frank Gubler
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Crispin A Howitt
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Barry J Pogson
- ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, ACT, Australia
| | - Matthew K Morell
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
| | - Jean-Philippe Ral
- Agriculture Flagship, Commonwealth Science and Industrial Research Organisation, Canberra, ACT, Australia
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46
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Meekins DA, Raththagala M, Auger KD, Turner BD, Santelia D, Kötting O, Gentry MS, Vander Kooi CW. Mechanistic Insights into Glucan Phosphatase Activity against Polyglucan Substrates. J Biol Chem 2015; 290:23361-70. [PMID: 26231210 DOI: 10.1074/jbc.m115.658203] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Indexed: 01/11/2023] Open
Abstract
Glucan phosphatases are central to the regulation of starch and glycogen metabolism. Plants contain two known glucan phosphatases, Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), which dephosphorylate starch. Starch is water-insoluble and reversible phosphorylation solubilizes its outer surface allowing processive degradation. Vertebrates contain a single known glucan phosphatase, laforin, that dephosphorylates glycogen. In the absence of laforin, water-soluble glycogen becomes insoluble, leading to the neurodegenerative disorder Lafora Disease. Because of their essential role in starch and glycogen metabolism glucan phosphatases are of significant interest, yet a comparative analysis of their activities against diverse glucan substrates has not been established. We identify active site residues required for specific glucan dephosphorylation, defining a glucan phosphatase signature motif (CζAGΨGR) in the active site loop. We further explore the basis for phosphate position-specific activity of these enzymes and determine that their diverse phosphate position-specific activity is governed by the phosphatase domain. In addition, we find key differences in glucan phosphatase activity toward soluble and insoluble polyglucan substrates, resulting from the participation of ancillary glucan-binding domains. Together, these data provide fundamental insights into the specific activity of glucan phosphatases against diverse polyglucan substrates.
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Affiliation(s)
- David A Meekins
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536
| | - Madushi Raththagala
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536
| | - Kyle D Auger
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536
| | - Benjamin D Turner
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536
| | - Diana Santelia
- Institute of Plant Biology, University of Zürich, CH-8008, Zürich, Switzerland, and
| | - Oliver Kötting
- Institute of Agricultural Sciences, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8092, Zürich, Switzerland
| | - Matthew S Gentry
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536,
| | - Craig W Vander Kooi
- From the Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536,
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Santelia D, Trost P, Sparla F. New insights into redox control of starch degradation. CURRENT OPINION IN PLANT BIOLOGY 2015; 25:1-9. [PMID: 25899330 DOI: 10.1016/j.pbi.2015.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/31/2015] [Accepted: 04/03/2015] [Indexed: 05/04/2023]
Abstract
Starch is one of the major sinks of fixed carbon in photosynthetic tissues of higher plants. Carbon fixation and the synthesis of primary starch occur during the day in the chloroplast stroma, whereas starch degradation typically occurs during the following night to fuel the whole plant with energy and carbon in the absence of photosynthesis. Redox-based regulatory systems play a central role in the modulation of several chloroplastic pathways. Reversible oxidations of cysteine residues are post-translational modifications that orchestrate the precise functioning of chloroplast pathways together with changes in pH, Mg(2+) and concentrations of metabolic intermediates. Leaf starch metabolism has been intensively studied. The enzymes involved in starch synthesis and degradation have been identified and characterized. However, the redox control of the enzymes responsible for starch degradation at night remains elusive, and their response to redox transitions conflicts with the timing of the physiological events. Most of the enzymes of starch degradation are activated by reducing conditions, characteristic of daytime. Thus, redox control may have only a minor role during starch degradation at night, but could become relevant for daily stomatal opening in guard cells or in the re-allocation of fixed carbon in mesophyll cells in response to stress conditions.
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Affiliation(s)
- Diana Santelia
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
| | - Paolo Trost
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy
| | - Francesca Sparla
- Department of Pharmacy and Biotechnology FaBiT, University of Bologna, Via Irnerio 42, 40126 Bologna, Italy.
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Transitory and storage starch metabolism: two sides of the same coin? Curr Opin Biotechnol 2015; 32:143-148. [DOI: 10.1016/j.copbio.2014.11.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/25/2014] [Accepted: 11/28/2014] [Indexed: 11/19/2022]
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Palmer WM, Ru L, Jin Y, Patrick JW, Ruan YL. Tomato ovary-to-fruit transition is characterized by a spatial shift of mRNAs for cell wall invertase and its inhibitor with the encoded proteins localized to sieve elements. MOLECULAR PLANT 2015; 8:315-28. [PMID: 25680776 DOI: 10.1016/j.molp.2014.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/20/2014] [Accepted: 12/17/2014] [Indexed: 05/08/2023]
Abstract
Central to understanding fruit development is to elucidate the processes mediating a successful transition from pre-pollination ovaries to newly set fruit, a key step in establishing fruit yield potential. In tomato, cell wall invertase (CWIN) LIN5 and its inhibitor INH1 are essential for fruit growth. However, the molecular and cellular basis by which they exert their roles in ovary-to-fruit transition remains unknown. To address this issue, we conducted a study focusing on ovaries and fruitlets at 2 days before and 2 days after anthesis, respectively. In situ hybridization analyses revealed that LIN5 and INH1 exhibited a dispersed expression in ovaries compared with their phloem-specific expression in fruitlets. Remarkably, LIN5 and INH1 proteins were immunologically co-localized to cell walls of sieve elements (SEs) in ovaries immediately prior to anthesis and in young fruitlets, but were undetectable in provascular bundles of younger ovaries. A burst in CWIN activity occurred during ovary-to-fruit transition. Interestingly, the ovaries, but not the fruitlets, exhibited high expression of a defective invertase, SldeCWIN1, an ortholog of which is known to enhance inhibition of INH on CWIN activity in tobacco. Imaging of a fluorescent symplasmic tracer indicated an apoplasmic phloem unloading pathway operated in ovaries, contrary to the previously observed symplasmic unloading pathway in fruit pericarp. These new data indicate that (1) a phloem-specific patterning of the CWIN and INH mRNAs is induced during ovary-to-fruit transition, and (2) LIN5 protein functions specifically in walls of SEs and increases its activity during ovary-to-fruit transition, probably to facilitate phloem unloading and to generate a glucose signal positively regulating cell division, hence fruit set.
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Affiliation(s)
- William M Palmer
- School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Callaghan, Australia; Australia-China Research Centre for Crop Improvement, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Lei Ru
- School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Callaghan, Australia; Australia-China Research Centre for Crop Improvement, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Ye Jin
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China
| | - John W Patrick
- School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Callaghan, Australia; Australia-China Research Centre for Crop Improvement, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Yong-Ling Ruan
- School of Environmental and Life Sciences, The University of Newcastle, NSW 2308, Callaghan, Australia; Australia-China Research Centre for Crop Improvement, The University of Newcastle, NSW 2308, Callaghan, Australia.
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Scialdone A, Howard M. How plants manage food reserves at night: quantitative models and open questions. FRONTIERS IN PLANT SCIENCE 2015; 6:204. [PMID: 25873925 PMCID: PMC4379750 DOI: 10.3389/fpls.2015.00204] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/14/2015] [Indexed: 05/18/2023]
Abstract
In order to cope with night-time darkness, plants during the day allocate part of their photosynthate for storage, often as starch. This stored reserve is then degraded at night to sustain metabolism and growth. However, night-time starch degradation must be tightly controlled, as over-rapid turnover results in premature depletion of starch before dawn, leading to starvation. Recent experiments in Arabidopsis have shown that starch degradation proceeds at a constant rate during the night and is set such that starch reserves are exhausted almost precisely at dawn. Intriguingly, this pattern is robust with the degradation rate being adjusted to compensate for unexpected changes in the time of darkness onset. While a fundamental role for the circadian clock is well-established, the underlying mechanisms controlling starch degradation remain poorly characterized. Here, we discuss recent quantitative models that have been proposed to explain how plants can compute the appropriate starch degradation rate, a process that requires an effective arithmetic division calculation. We review experimental confirmation of the models, and describe aspects that require further investigation. Overall, the process of night-time starch degradation necessitates a fundamental metabolic role for the circadian clock and, more generally, highlights how cells process information in order to optimally manage their resources.
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Affiliation(s)
- Antonio Scialdone
- Wellcome Trust Sanger Institute, Wellcome Trust Genome CampusHinxton, Cambridge, UK
- European Molecular Biology Laboratory-European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome CampusHinxton, Cambridge, UK
| | - Martin Howard
- Computational and Systems Biology, John Innes CentreNorwich, UK
- *Correspondence: Martin Howard, Computational and Systems Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich, NR4 7UH, UK
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