Relevance of oligofructans for endosperm formation and filling during cereal grain development

低聚果聚糖与谷物发育过程中胚乳形成和灌浆的相关性

• 批准号: 279623785
• 负责人: Dr. Manuela Peukert
• 金额: --
• 依托单位: Department of Crop Genetics
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/279623785?language=en
• 关键词: Relevance; oligofructans; endosperm; formation; filling

Cereal grain development is characterized by tremendous structural and physiological changes reflected by the development and degeneration of tissues and a massive production of storage compounds (starch, proteins and lipids). These developmental processes have been shown to correlate to distinct metabolite distribution patterns. Among them, a spatiotemporally regulated accumulation of various fructan types was revealed pointing towards developmental phase dependent functions in grain tissues. During the prestorage phase levan- and graminan-type oligofructans are synthesized in the cellularized endosperm just before the beginning of massive biosynthesis of starch. The conversion of sucrose into fructans is deemed to keep the sucrose level low and thus to prevent premature differentiation of storage cells until cellularization of the endosperm has finished. During the storage phase inulin-type oligofructans are synthesized in the nucellar projection (NP), and these fructans accumulate in endosperm transfer cells (ETC) and the endosperm cavity. The inulins are assumed to act as antioxidants in transport active tissues to maintain high rates of assimilate import into the endosperm. This project will address and further investigate the hypothesized roles of grain fructan metabolism. Generation of transgenic RNAi and CRISPR barley lines with suppressed biosynthesis of particular fructan types will be a tool to monitor alterations in grain development in respect to the level of the distinct oligofructan types. A reduction of endosperm specific fructans by knock-down of the sucrose:fructan 6-fructosyltransferase (6-SFT) is expected to induce a lowered cellularisation during the prestorage phase and consequently a reduced final grain weight. A suppressed accumulation of inulin-type fructans in transfer tissues by knock-out of the sucrose:sucrose 1-fructosyltransferase (1-SST) is expected to negatively affect the import of assimilates into the developing endosperm due to increased oxidative stress. Limitations in nutrient import will result in reduced final grain weight and quality. The genetic approach will be complemented with subcellular localization studies of inulin-type fructans and fructan biosynthesis enzymes. Furthermore, in vitro experiments with artificial membranes will be used to study the role of fructans as antioxidants in greater detail. The results of this study will contribute to unravelling the as yet unknown functions of oligofructans in grain developmental processes and their impact on final grain quality. Additionally, characterisation of grain fructan physiology will reveal details of overall sugar regulatory networks.

谷物发育的特点是组织的发育和退化以及储存化合物（淀粉、蛋白质和脂质）的大量产生所反映的巨大的结构和生理变化。这些发育过程已被证明与不同的代谢物分布模式相关。其中，揭示了各种果聚糖类型的时空调节积累，表明谷物组织中的发育阶段依赖性功能。在预储存阶段，果聚糖和禾谷聚糖型低聚果聚糖在淀粉大量生物合成开始之前在细胞化的胚乳中合成。蔗糖转化为果聚糖被认为可以保持较低的蔗糖水平，从而防止储存细胞过早分化，直到胚乳的细胞化完成。在储存阶段，菊粉型低聚果聚糖在珠心突起（NP）中合成，并且这些果聚糖在胚乳转移细胞（ETC）和胚乳腔中积累。菊粉被认为在运输活性组织中充当抗氧化剂，以维持胚乳高同化物输入率。 该项目将解决并进一步研究谷物果聚糖代谢的假设作用。产生抑制特定果聚糖类型生物合成的转基因RNAi和CRISPR大麦品系将成为监测谷物发育中不同低聚果聚糖类型水平变化的工具。通过敲低蔗糖：果聚糖 6-果糖基转移酶 (6-SFT) 来减少胚乳特异性果聚糖，预计会导致预贮期细胞化程度降低，从而降低最终粒重。通过敲除蔗糖：蔗糖1-果糖基转移酶（1-SST）来抑制转移组织中菊粉型果聚糖的积累，预计由于氧化应激增加，会对同化物进入发育中的胚乳产生负面影响。养分进口的限制将导致最终谷物重量和质量下降。遗传方法将与菊粉型果聚糖和果聚糖生物合成酶的亚细胞定位研究相补充。此外，人工膜体外实验将用于更详细地研究果聚糖作为抗氧化剂的作用。这项研究的结果将有助于揭示低聚果聚糖在谷物发育过程中的未知功能及其对最终谷物质量的影响。此外，谷物果聚糖生理学的表征将揭示整体糖调节网络的细节。