1
|
Li X, Ahmad AM, Zhong Y, Ding L, Blennow A, Fettke J. Starch phosphorylation regulates starch granule morphological homogeneity in Arabidopsis thaliana. PLANT PHYSIOLOGY 2024; 194:2600-2615. [PMID: 38060678 PMCID: PMC10980398 DOI: 10.1093/plphys/kiad656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 11/13/2023] [Indexed: 04/01/2024]
Abstract
Starch granule morphological homogeneity presents a gap in starch research. Transitory starch granules in wild-type plants are discoid, regardless of species. Notably, while the shape of starch granules can differ among mutants, it typically remains homogeneous within a genotype. We found an Arabidopsis thaliana mutant, dpe2sex4, lacking both the cytosolic disproportionating enzyme 2 (DPE2) and glucan phosphatase SEX4, showing an unprecedented bimodal starch granule diameter distribution when grown under a light/dark rhythm. dpe2sex4 contained 2 types of starch granules: large granules and small granules. In contrast to the double starch initiation in wheat (Triticum aestivum) endosperm, where A-type granules are initiated first and B-type granules are initiated later, dpe2sex4 small and large granules developed simultaneously in the same chloroplast. Compared with the large granules, the small granules had more branched amylopectin and less surface starch-phosphate, thus having a more compact structure that may hinder starch synthesis. During plant aging, the small granules barely grew. In in vitro experiments, fewer glucosyl residues were incorporated in small granules. Under continuous light, dpe2sex4 starch granules were morphologically homogeneous. Omitting the dark phase after a 2-wk light/dark cycle by moving plants into continuous light also reduced morphological variance between these 2 types of granules. These data shed light on the impact of starch phosphorylation on starch granule morphology homogeneity.
Collapse
Affiliation(s)
- Xiaoping Li
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm 14776, Germany
| | - Abubakar Musa Ahmad
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm 14776, Germany
| | - Yuyue Zhong
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C 1871, Denmark
| | - Li Ding
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C 1871, Denmark
| | - Andreas Blennow
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C 1871, Denmark
| | - Joerg Fettke
- Biopolymer Analytics, Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm 14776, Germany
| |
Collapse
|
2
|
Cheng K, Pan YF, Liu LM, Zhang HQ, Zhang YM. Integrated Transcriptomic and Bioinformatics Analyses Reveal the Molecular Mechanisms for the Differences in Seed Oil and Starch Content Between Glycine max and Cicer arietinum. FRONTIERS IN PLANT SCIENCE 2021; 12:743680. [PMID: 34764968 PMCID: PMC8576049 DOI: 10.3389/fpls.2021.743680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
The seed oil and starch content of soybean are significantly different from that of chickpea. However, there are limited studies on its molecular mechanisms. To address this issue, we conducted integrated transcriptomic and bioinformatics analyses for species-specific genes and acyl-lipid-, starch-, and carbon metabolism-related genes. Among seven expressional patterns of soybean-specific genes, four were highly expressed at the middle- and late oil accumulation stages; these genes significantly enriched fatty acid synthesis and carbon metabolism, and along with common acetyl CoA carboxylase (ACCase) highly expressed at soybean middle seed development stage, common starch-degrading enzyme beta-amylase-5 (BAM5) was highly expressed at soybean early seed development stage and oil synthesis-related genes ACCase, KAS, KAR, ACP, and long-chain acyl-CoA synthetase (LACS) were co-expressed with WRI1, which may result in high seed oil content and low seed starch content in soybean. The common ADP-glucose pyrophosphorylase (AGPase) was highly expressed at chickpea middle seed development stage, along with more starch biosynthesis genes co-expressed with four-transcription-factor homologous genes in chickpea than in soybean, and the common WRI1 was not co-expressed with oil synthesis genes in chickpea, which may result in high seed starch content and low seed oil content in chickpea. The above results may be used to improve chickpea seed oil content in two ways. One is to edit CaWRI1 to co-express with oil synthesis-related genes, which may increase carbon metabolites flowing to oil synthesis, and another is to increase the expression levels of miRNA159 and miRNA319 to inhibit the expression of MYB33, which may downregulate starch synthesis-related genes, making more carbon metabolites flow into oil synthesis. Our study will provide a basis for future breeding efforts to increase the oil content of chickpea seeds.
Collapse
|
3
|
Starch and Glycogen Analyses: Methods and Techniques. Biomolecules 2020; 10:biom10071020. [PMID: 32660096 PMCID: PMC7407607 DOI: 10.3390/biom10071020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 01/16/2023] Open
Abstract
For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included.
Collapse
|
4
|
Abstract
The starch-rich endosperms of the Poaceae, which includes wild grasses and their domesticated descendents the cereals, have provided humankind and their livestock with the bulk of their daily calories since the dawn of civilization up to the present day. There are currently unprecedented pressures on global food supplies, largely resulting from population growth, loss of agricultural land that is linked to increased urbanization, and climate change. Since cereal yields essentially underpin world food and feed supply, it is critical that we understand the biological factors contributing to crop yields. In particular, it is important to understand the biochemical pathway that is involved in starch biosynthesis, since this pathway is the major yield determinant in the seeds of six out of the top seven crops grown worldwide. This review outlines the critical stages of growth and development of the endosperm tissue in the Poaceae, including discussion of carbon provision to the growing sink tissue. The main body of the review presents a current view of our understanding of storage starch biosynthesis, which occurs inside the amyloplasts of developing endosperms.
Collapse
|
5
|
Simultaneous silencing of isoamylases ISA1, ISA2 and ISA3 by multi-target RNAi in potato tubers leads to decreased starch content and an early sprouting phenotype. PLoS One 2017; 12:e0181444. [PMID: 28708852 PMCID: PMC5510849 DOI: 10.1371/journal.pone.0181444] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/02/2017] [Indexed: 01/16/2023] Open
Abstract
Isoamylases hydrolyse (1–6)-alpha-D-glucosidic linkages in starch and are involved in both starch granule formation and starch degradation. In plants, three isoamylase isoforms with distinct functions in starch synthesis (ISA1 and ISA2) and degradation (ISA3) have been described. Here, we created transgenic potato plants with simultaneously decreased expression of all three isoamylases using a chimeric RNAi construct targeting all three isoforms. Constitutive expression of the hairpin RNA using the 35S CaMV promoter resulted in efficient silencing of all three isoforms in leaves, growing tubers, and sprouting tubers. Neither plant growth nor tuber yield was effected in isoamylase-deficient potato lines. Interestingly, starch metabolism was found to be impaired in a tissue-specific manner. While leaf starch content was unaffected, tuber starch was significantly reduced. The reduction in tuber starch content in the transgenic plants was accompanied by a decrease in starch granules size, an increased sucrose content and decreased hexose levels. Despite the effects on granule size, only little changes in chain length composition of soluble and insoluble glucose polymers were detected. The transgenic tubers displayed an early sprouting phenotype that was accompanied by an increased level of sucrose in parenchyma cells below the outgrowing bud. Since high sucrose levels promote sprouting, we propose that the increased number of small starch granules may cause an accelerated turnover of glucan chains and hence a more rapid synthesis of sucrose. This observation links alterations in starch structure/degradation with developmental processes like meristem activation and sprout outgrowth in potato tubers.
Collapse
|
6
|
Pfister B, Sánchez-Ferrer A, Diaz A, Lu K, Otto C, Holler M, Shaik FR, Meier F, Mezzenga R, Zeeman SC. Recreating the synthesis of starch granules in yeast. eLife 2016; 5:e15552. [PMID: 27871361 PMCID: PMC5119888 DOI: 10.7554/elife.15552] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 10/08/2016] [Indexed: 11/13/2022] Open
Abstract
Starch, as the major nutritional component of our staple crops and a feedstock for industry, is a vital plant product. It is composed of glucose polymers that form massive semi-crystalline granules. Its precise structure and composition determine its functionality and thus applications; however, there is no versatile model system allowing the relationships between the biosynthetic apparatus, glucan structure and properties to be explored. Here, we expressed the core Arabidopsis starch-biosynthesis pathway in Saccharomyces cerevisiae purged of its endogenous glycogen-metabolic enzymes. Systematic variation of the set of biosynthetic enzymes illustrated how each affects glucan structure and solubility. Expression of the complete set resulted in dense, insoluble granules with a starch-like semi-crystalline organization, demonstrating that this system indeed simulates starch biosynthesis. Thus, the yeast system has the potential to accelerate starch research and help create a holistic understanding of starch granule biosynthesis, providing a basis for the targeted biotechnological improvement of crops.
Collapse
Affiliation(s)
| | | | - Ana Diaz
- Paul Scherrer Institut, Villigen, Switzerland
| | - Kuanjen Lu
- Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Caroline Otto
- Department of Biology, ETH Zürich, Zürich, Switzerland
| | | | | | | | | | | |
Collapse
|
7
|
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.
Collapse
Affiliation(s)
- Barbara Pfister
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Samuel C Zeeman
- Department of Biology, ETH Zurich, 8092, Zurich, Switzerland.
| |
Collapse
|
8
|
Suzuki E, Suzuki R. Distribution of glucan-branching enzymes among prokaryotes. Cell Mol Life Sci 2016; 73:2643-60. [PMID: 27141939 PMCID: PMC11108348 DOI: 10.1007/s00018-016-2243-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [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: 12/12/2022]
Abstract
Glucan-branching enzyme plays an essential role in the formation of branched polysaccharides, glycogen, and amylopectin. Only one type of branching enzyme, belonging to glycoside hydrolase family 13 (GH13), is found in eukaryotes, while two types of branching enzymes (GH13 and GH57) occur in prokaryotes (Bacteria and Archaea). Both of these types are the members of protein families containing the diverse specificities of amylolytic glycoside hydrolases. Although similarities are found in the catalytic mechanism between the two types of branching enzyme, they are highly distinct from each other in terms of amino acid sequence and tertiary structure. Branching enzymes are found in 29 out of 30 bacterial phyla and 1 out of 5 archaeal phyla, often along with glycogen synthase, suggesting the existence of α-glucan production and storage in a wide range of prokaryotes. Enormous variability is observed as to which type and how many copies of branching enzyme are present depending on the phylum and, in some cases, even among species of the same genus. Such a variation may have occurred through lateral transfer, duplication, and/or differential loss of genes coding for branching enzyme during the evolution of prokaryotes.
Collapse
Affiliation(s)
- Eiji Suzuki
- Department of Biological Production, Akita Prefectural University, 241-438, Kaidobata-Nishi, Shimoshinjyo-Nakano, Akita, 010-0195, Japan.
| | - Ryuichiro Suzuki
- Department of Biological Production, Akita Prefectural University, 241-438, Kaidobata-Nishi, Shimoshinjyo-Nakano, Akita, 010-0195, Japan
| |
Collapse
|