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Guo J, Yang Y, Wang T, Wang Y, Zhang X, Min D, Zhang X. Analysis of Raffinose Synthase Gene Family in Bread Wheat and Identification of Drought Resistance and Salt Tolerance Function of TaRS15-3B. Int J Mol Sci 2023; 24:11185. [PMID: 37446364 DOI: 10.3390/ijms241311185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 06/26/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023] Open
Abstract
Raffinose synthase (RS) plays a crucial role in plant growth and development, as well as in responses to biotic stresses and abiotic stresses, yet few studies have been conducted on its role in bread wheat. Therefore, in this study we screened and identified a family of bread wheat raffinose synthase genes based on bread wheat genome information and analyzed their physicochemical properties, phylogenetic evolutionary relationships, conserved structural domains, promoter cis-acting elements, and expression patterns. The BSMV-induced silencing of TaRS15-3B resulted in the bread wheat seedlings being susceptible to drought and salt stress and reduced the expression levels of stress-related and ROS-scavenging genes in bread wheat plants. This further affected the ability of bread wheat to cope with drought and salt stress. In conclusion, this study revealed that the RS gene family in bread wheat plays an important role in plant response to abiotic stresses and that the TaRS15-3B gene can improve the tolerance of transgenic bread wheat to drought and salt stresses, provide directions for the study of other RS gene families in bread wheat, and supply candidate genes for use in molecular breeding of bread wheat for stress resistance.
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Affiliation(s)
- Jiagui Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Xianyang 712100, China
| | - Yan Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Xianyang 712100, China
| | - Tingting Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Xianyang 712100, China
| | - Yizhen Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Xianyang 712100, China
| | - Xin Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Xianyang 712100, China
| | - Donghong Min
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Xianyang 712100, China
| | - Xiaohong Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Xianyang 712100, China
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Xu J, You X, Leng Y, Li Y, Lu Z, Huang Y, Chen M, Zhang J, Song T, Liu T. Identification and Alternative Splicing Profile of the Raffinose synthase Gene in Grass Species. Int J Mol Sci 2023; 24:11120. [PMID: 37446297 DOI: 10.3390/ijms241311120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/30/2023] [Accepted: 07/02/2023] [Indexed: 07/15/2023] Open
Abstract
Raffinose synthase (Rafs) is an important enzyme in the synthesis pathway of raffinose from sucrose and galactinol in higher plants and is involved in the regulation of seed development and plant responses to abiotic stresses. In this study, we analyzed the Rafs families and profiled their alternative splicing patterns at the genome-wide scale from 10 grass species representing crops and grasses. A total of 73 Rafs genes were identified from grass species such as rice, maize, foxtail millet, and switchgrass. These Rafs genes were assigned to six groups based the phylogenetic analysis. We compared the gene structures, protein domains, and expression patterns of Rafs genes, and also unraveled the alternative transcripts of them. In addition, different conserved sequences were observed at these putative splice sites among grass species. The subcellular localization of PvRafs5 suggested that the Rafs gene was expressed in the cytoplasm or cell membrane. Our findings provide comprehensive knowledge of the Rafs families in terms of genes and proteins, which will facilitate further functional characterization in grass species in response to abiotic stress.
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Affiliation(s)
- Junhao Xu
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
| | - Xiangkai You
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
| | - Yanan Leng
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210000, China
| | - Youyue Li
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
| | - Zeyu Lu
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
| | - Yinan Huang
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
| | - Moxian Chen
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210000, China
| | - Jianhua Zhang
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Tao Song
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210000, China
| | - Tieyuan Liu
- College of Grassland Agriculture, Northwest A&F University, Yangling 712100, China
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3
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Jing Q, Chen A, Lv Z, Dong Z, Wang L, Meng X, Feng Y, Wan Y, Su C, Cui Y, Xu W, Hou H, Zhu X. Systematic Analysis of Galactinol Synthase and Raffinose Synthase Gene Families in Potato and Their Expression Patterns in Development and Abiotic Stress Responses. Genes (Basel) 2023; 14:1344. [PMID: 37510251 PMCID: PMC10379439 DOI: 10.3390/genes14071344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 06/19/2023] [Accepted: 06/25/2023] [Indexed: 07/30/2023] Open
Abstract
Raffinose family oligosaccharides (RFOs) are very important for plant growth, development, and abiotic stress tolerance. Galactinol synthase (GolS) and raffinose synthase (RFS) are critical enzymes involved in RFO biosynthesis. However, the whole-genome identification and stress responses of their coding genes in potato remain unexplored. In this study, four StGolS and nine StRFS genes were identified and classified into three and five subgroups, respectively. Remarkably, a total of two StGolS and four StRFS genes in potato were identified to form collinear pairs with those in both Arabidopsis and tomato, respectively. Subsequent analysis revealed that StGolS4 exhibited significantly high expression levels in transport-related tissues, PEG-6000, and ABA treatments, with remarkable upregulation under salt stress. Additionally, StRFS5 showed similar responses to StGolS4, but StRFS4 and StRFS8 gene expression increased significantly under salt treatment and decreased in PEG-6000 and ABA treatments. Overall, these results lay a foundation for further research on the functional characteristics and molecular mechanisms of these two gene families in response to ABA, salt, and drought stresses, and provide a theoretical foundation and new gene resources for the abiotic-stress-tolerant breeding of potato.
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Affiliation(s)
- Quankai Jing
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Airu Chen
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Zhaoyan Lv
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Zhihao Dong
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Lixia Wang
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Xiaoke Meng
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Yue Feng
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Yu Wan
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Chengyun Su
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Yanjie Cui
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Wenjuan Xu
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Hualan Hou
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
| | - Xiaobiao Zhu
- School of Horticulture, Anhui Agricultural University, Hefei 230000, China
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Wang T, Wang Y, Zhao J, Kong J, Zhang L, Qi S, Chen J, Chen Z, Zeng W, Sun W. Identification, Characterization and Expression Profiling of the RS Gene Family during the Withering Process of White Tea in the Tea Plant ( Camellia sinensis) Reveal the Transcriptional Regulation of CsRS8. Int J Mol Sci 2022; 24:ijms24010202. [PMID: 36613645 PMCID: PMC9820808 DOI: 10.3390/ijms24010202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/17/2022] [Accepted: 12/18/2022] [Indexed: 12/25/2022] Open
Abstract
Raffinose synthetase (RS) is a key enzyme in the process of raffinose (Raf) synthesis and is involved in plant development and stress responses through regulating Raf content. As a sweetener, Raf makes an important contribution to the sweet taste of white tea. However, studies on the identification, analysis and transcriptional regulation of CsRSs (Camellia sinensis RS genes) are still lacking. In this study, nine CsRSs were identified from the tea plant (Camellia sinensis) genome database. The CsRSs were classified into five groups in the phylogenetic tree. Expression level analysis showed that the CsRSs varied in different parts of the tea plant. Transcriptome data showed that CsRSs could respond to persistent drought and cold acclimation. Except for CsRS5 and CsRS9, the expression pattern of all CsRSs increased at 12 h and decreased at 30 h during the withering process of white tea, consistent with the change trend of the Raf content. Furthermore, combining yeast one-hybrid assays with expression analysis, we found that CsDBB could potentially regulate the expression of CsRS8. Our results provide a new perspective for further research into the characterization of CsRS genes and the formation of the white tea flavour.
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Affiliation(s)
- Tao Wang
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yiqing Wang
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiamin Zhao
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiumei Kong
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lingzhi Zhang
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Siyu Qi
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiajia Chen
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zhidan Chen
- Anxi College of Tea Science, Fujian Agriculture and Forestry University, Quanzhou 362000, China
| | - Wen Zeng
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (W.Z.); (W.S.)
| | - Weijiang Sun
- College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (W.Z.); (W.S.)
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Khan M, Hu J, Dahro B, Ming R, Zhang Y, Wang Y, Alhag A, Li C, Liu JH. ERF108 from Poncirus trifoliata (L.) Raf. functions in cold tolerance by modulating raffinose synthesis through transcriptional regulation of PtrRafS. Plant J 2021; 108:705-724. [PMID: 34398993 DOI: 10.1111/tpj.15465] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/07/2021] [Accepted: 08/12/2021] [Indexed: 05/21/2023]
Abstract
Ethylene-responsive factors (ERFs) are plant-specific transcription factors involved in cold stress response, and raffinose is known to accumulate in plants exposed to cold. However, it remains elusive whether ERFs function in cold tolerance by modulating raffinose synthesis. Here, we identified a cold-responsive PtrERF108 from trifoliate orange (Poncirus trifoliata (L.) Raf.), a cold-tolerant plant closely related to citrus. PtrERF108 is localized in the nucleus and has transcriptional activation activity. Overexpression of PtrERF108 conferred enhanced cold tolerance of transgenic lemon, whereas virus-induced gene silencing (VIGS)-mediated knockdown of PtrERF108 in trifoliate orange greatly elevated cold sensitivity. Transcriptome profiling showed that PtrERF108 overexpression caused extensive reprogramming of genes associated with signaling transduction, physiological processes and metabolic pathways. Among them, a raffinose synthase (RafS)-encoding gene, PtrRafS, was confirmed as a direct target of PtrERF108. RafS activity and raffinose content were significantly increased in PtrERF108-overexpressing transgenic plants, but prominently decreased in the VIGS plants under cold conditions. Meanwhile, exogenous replenishment of raffinose could recover the cold tolerance of PtrERF108-silenced plants, whereas VIGS-mediated knockdown of PtrRafS resulted in cold-sensitive phenotype. Taken together, the current results demonstrate that PtrERF108 plays a positive role in cold tolerance by modulation of raffinose synthesis via regulating PtrRafS. Our findings reveal a new transcriptional module composed of ERF108-RafS underlying cold-induced raffinose accumulation in plants.
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Affiliation(s)
- Madiha Khan
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jianbing Hu
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Bachar Dahro
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ruhong Ming
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yang Zhang
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yue Wang
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ahmed Alhag
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chunlong Li
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ji-Hong Liu
- Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
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Li T, Zhang Y, Liu Y, Li X, Hao G, Han Q, Dirk LMA, Downie AB, Ruan YL, Wang J, Wang G, Zhao T. Raffinose synthase enhances drought tolerance through raffinose synthesis or galactinol hydrolysis in maize and Arabidopsis plants. J Biol Chem 2020; 295:8064-8077. [PMID: 32366461 DOI: 10.1074/jbc.ra120.013948] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 04/29/2020] [Indexed: 11/06/2022] Open
Abstract
Raffinose and its precursor galactinol accumulate in plant leaves during abiotic stress. RAFFINOSE SYNTHASE (RAFS) catalyzes raffinose formation by transferring a galactosyl group of galactinol to sucrose. However, whether RAFS contributes to plant drought tolerance and, if so, by what mechanism remains unclear. In this study, we report that expression of RAFS from maize (or corn, Zea mays) (ZmRAFS) is induced by drought, heat, cold, and salinity stresses. We found that zmrafs mutant maize plants completely lack raffinose and hyper-accumulate galactinol and are more sensitive to drought stress than the corresponding null-segregant (NS) plants. This indicated that ZmRAFS and its product raffinose contribute to plant drought tolerance. ZmRAFS overexpression in Arabidopsis enhanced drought stress tolerance by increasing myo-inositol levels via ZmRAFS-mediated galactinol hydrolysis in the leaves due to sucrose insufficiency in leaf cells and also enhanced raffinose synthesis in the seeds. Supplementation of sucrose to detached leaves converted ZmRAFS from hydrolyzing galactinol to synthesizing raffinose. Taken together, we demonstrate that ZmRAFS enhances plant drought tolerance through either raffinose synthesis or galactinol hydrolysis, depending on sucrose availability in plant cells. These results provide new avenues to improve plant drought stress tolerance through manipulation of the raffinose anabolic pathway.
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Affiliation(s)
- Tao Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China.,State Key Laboratory of Wheat and Maize Crop Science, Collaborative Innovation Center of Henan Grain Crops, College of Life Science, Henan Agricultural University, Zhengzhou, Henan, China
| | - Yumin Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Ying Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Xudong Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Guanglong Hao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Qinghui Han
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China.,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
| | - Lynnette M A Dirk
- Department of Horticulture, Seed Biology, College of Agriculture, Food, and Environment, University of Kentucky, Lexington, Kentucky, USA
| | - A Bruce Downie
- Department of Horticulture, Seed Biology, College of Agriculture, Food, and Environment, University of Kentucky, Lexington, Kentucky, USA
| | - Yong-Ling Ruan
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
| | - Jianmin Wang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Guoying Wang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Tianyong Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China .,The Key Laboratory of Biology and Genetics Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Northwest A&F University, Yangling, Shaanxi, China
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Gangl R, Tenhaken R. Raffinose Family Oligosaccharides Act As Galactose Stores in Seeds and Are Required for Rapid Germination of Arabidopsis in the Dark. Front Plant Sci 2016; 7:1115. [PMID: 27507985 PMCID: PMC4960254 DOI: 10.3389/fpls.2016.01115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 07/13/2016] [Indexed: 05/25/2023]
Abstract
Raffinose synthase 5 (AtRS5, At5g40390) was characterized from Arabidopsis as a recombinant enzyme. It has a far higher affinity for the substrates galactinol and sucrose than any other raffinose synthase previously reported. In addition raffinose synthase 5 is also working as a galactosylhydrolase, degrading galactinol, and raffinose under certain conditions. Together with raffinose synthase 4, which is predominantly a stachyose synthase, both enzymes contribute to the raffinose family oligosaccharide (RFO) accumulation in seeds. A double knockout in raffinose synthase 4 and raffinose synthase 5 (ΔAtRS4,5) was generated, which is devoid of RFOs in seeds. Unstressed leaves of 4 week old ΔAtRS4,5 plants showed drastically 23.8-fold increased concentrations of galactinol. Unexpectedly, raffinose appeared again in drought stressed ΔAtRS4,5 plants, but not under other abiotic stress conditions. Drought stress leads to novel transcripts of raffinose synthase 6 suggesting that this isoform is a further stress inducible raffinose synthase in Arabidopsis. ΔAtRS4,5 seeds showed a 5 days delayed germination phenotype in darkness and an elevated expression of the transcription factor phytochrome interacting factor 1 (AtPIF1) target gene AtPIF6, being a repressor of germination. This prolonged dormancy is not seen during germination in the light. Exogenous galactose partially promotes germination of ΔAtRS4,5 seeds in the dark suggesting that RFOs act as a galactose store and repress AtPIF6 transcripts.
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Affiliation(s)
| | - Raimund Tenhaken
- Department of Cell Biology, Division of Plant Physiology, University of SalzburgSalzburg, Austria
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Sengupta S, Mukherjee S, Basak P, Majumder AL. Significance of galactinol and raffinose family oligosaccharide synthesis in plants. Front Plant Sci 2015; 6:656. [PMID: 26379684 PMCID: PMC4549555 DOI: 10.3389/fpls.2015.00656] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 08/07/2015] [Indexed: 05/18/2023]
Abstract
Abiotic stress induces differential expression of genes responsible for the synthesis of raffinose family of oligosaccharides (RFOs) in plants. RFOs are described as the most widespread D-galactose containing oligosaccharides in higher plants. Biosynthesis of RFOs begin with the activity of galactinol synthase (GolS; EC 2.4.1.123), a GT8 family glycosyltransferase that galactosylates myo-inositol to produce galactinol. Raffinose and the subsequent higher molecular weight RFOs (Stachyose, Verbascose, and Ajugose) are synthesized from sucrose by the subsequent addition of activated galactose moieties donated by Galactinol. Interestingly, GolS, the key enzyme of this pathway is functional only in the flowering plants. It is thus assumed that RFO synthesis is a specialized metabolic event in higher plants; although it is not known whether lower plant groups synthesize any galactinol or RFOs. In higher plants, several functional importance of RFOs have been reported, e.g., RFOs protect the embryo from maturation associated desiccation, are predominant transport carbohydrates in some plant families, act as signaling molecule following pathogen attack and wounding and accumulate in vegetative tissues in response to a range of abiotic stresses. However, the loss-of-function mutants reported so far fail to show any perturbation in those biological functions. The role of RFOs in biotic and abiotic stress is therefore still in debate and their specificity and related components remains to be demonstrated. The present review discusses the biology and stress-linked regulation of this less studied extension of inositol metabolic pathway.
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Affiliation(s)
- Sonali Sengupta
- *Correspondence: Arun L. Majumder and Sonali Sengupta, Division of Plant Biology, Bose Institute, Centenary Campus, P-1/12, C.I.T. Road, Scheme - VIIM, Kolkata 700054, West Bengal, India, ;
| | - Sritama Mukherjee
- †Present address: Sritama Mukherjee, Department of Botany, Bethune College, Kolkata 700006, West Bengal, India
| | | | - Arun L. Majumder
- *Correspondence: Arun L. Majumder and Sonali Sengupta, Division of Plant Biology, Bose Institute, Centenary Campus, P-1/12, C.I.T. Road, Scheme - VIIM, Kolkata 700054, West Bengal, India, ;
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Egert A, Keller F, Peters S. Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase (RS5, At5g40390). BMC Plant Biol 2013; 13:218. [PMID: 24354450 PMCID: PMC3878221 DOI: 10.1186/1471-2229-13-218] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/09/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND The sucrosylgalactoside oligosaccharide raffinose (Raf, Suc-Gal1) accumulates in Arabidopsis leaves in response to a myriad of abiotic stresses. Whilst galactinol synthases (GolS), the first committed enzyme in Raf biosynthesis are well characterised in Arabidopsis, little is known of the second biosynthetic gene/enzyme raffinose synthase (RS). Conflicting reports suggest the existence of either one or six abiotic stress-inducible RSs (RS-1 to -6) occurring in Arabidopsis. Indirect evidence points to At5g40390 being responsible for low temperature-induced Raf accumulation in Arabidopsis leaves. RESULTS By heterologously expressing At5g40390 in E.coli, we demonstrate that crude extracts synthesise Raf in vitro, contrary to empty vector controls. Using two independent loss-of-function mutants for At5g40390 (rs 5-1 and 5-2), we confirm that this RS is indeed responsible for Raf accumulation during low temperature-acclimation (4°C), as previously reported. Surprisingly, leaves of mutant plants also fail to accumulate any Raf under diverse abiotic stresses including water-deficit, high salinity, heat shock, and methyl viologen-induced oxidative stress. Correlated to the lack of Raf under these abiotic stress conditions, both mutant plants lack the typical stress-induced RafS activity increase observed in the leaves of wild-type plants. CONCLUSIONS Collectively our findings point to a single abiotic stress-induced RS isoform (RS5, At5g40390) being responsible for Raf biosynthesis in Arabidopsis leaves. However, they do not support a single RS hypothesis since the seeds of both mutant plants still contained Raf, albeit at 0.5-fold lower concentration than seeds from wild-type plants, suggesting the existence of at least one other seed-specific RS. These results also unambiguously discount the existence of six stress-inducible RS isoforms suggested by recent reports.
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Affiliation(s)
- Aurélie Egert
- Institute of Plant Biology, Molecular Plant Physiology Division, University of Zürich, Zollikerstrasse 107, Zürich CH-8008, Switzerland
- Present address: Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel CH-4056, Switzerland
| | - Felix Keller
- Institute of Plant Biology, Molecular Plant Physiology Division, University of Zürich, Zollikerstrasse 107, Zürich CH-8008, Switzerland
| | - Shaun Peters
- Institute for Plant Biotechnology, Department of Genetics, Faculty of AgriSciences, Stellenbosch University, Matieland 7602, South Africa
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