The regulation of starch biosynthesis and intermediary metabolism in plants

植物淀粉生物合成和中间代谢的调控

• 批准号: RGPIN-2018-04789
• 负责人: Emes, Michael
• 金额: $ 2.91万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712367
• 关键词: regulation; starch; biosynthesis; intermediary; metabolism

Starch is an insoluble polymer that plays a critical role in the carbon economy of most plants on earth. It is composed of two glucose polymers: linear amylose, whose synthesis requires just a single enzyme; and the more highly branched amylopectin which requires the coordinated activity of the products of at least 10 genes. Starch is the major determinant of yield in domesticated cereals such as maize, wheat, and rice, whose high caloric content is critical for both human and animal consumption. It is also an important commodity in non-food industries where its functionality is dependent on the organisation of glucose residues within a tightly defined, semi-crystalline structure, the assembly of which remains poorly understood. Metabolism of starch underpins the interplay between genetic and metabolic decision-making in plants, dictating the timing and initiation of developmental processes including flowering and seed production. Its mobilisation is critical for the growth of plants, and we are beginning to understand that affecting its synthesis and structure in source tissues can have significant effects on productivity. My research is focussed on understanding: 1) the biochemical and molecular mechanisms which are responsible for starch synthesis and architecture 2) how plants allocate resource to support growth and development. We have shown that several enzymes involved in starch biosynthesis form heteromeric complexes, working together physically and synergistically to produce the major component of starch, amylopectin. Assembly of these complexes is controlled post-translationally by protein kinases located within either amyloplasts of developing seeds or chloroplasts of leaves where starch is made. Recently we discovered that by changing the particular isoforms of starch branching enzymes involved in amylopectin synthesis in the model plant, Arabidopsis thaliana, not only was it possible to modify the structure of amylopectin, but there were profound, positive changes in biomass and seed production offering new opportunities to enhance the yield of oilseed crops. We have also identified a non-catalytic subunit of a global regulator of metabolism, SnRK1, which has significant effects on the utilisation of carbohydrate and integrates the metabolism of organic acids, lipids and the uptake of nitrate. Thus the main goals of this proposal are to 1) understand how post-translational mechanisms affect both the amount and structure of starch produced 2) identify the molecular, physiological and biochemical determinants which underpin the effective utilisation of starch for growth and development 3) investigate the role of global regulators of metabolism in controlling allocation of resources and nutrients to growth. We are well-poised to deliver such knowledge, providing opportunities for crop bioengineering to meet the challenges of a burgeoning global population.

淀粉是一种不溶性聚合物，在地球上大多数植物的碳经济中发挥着关键作用。 它由两种葡萄糖聚合物组成：线性直链淀粉，其合成只需要一种酶；支链度更高的支链淀粉需要至少 10 个基因产物的协调活性。 淀粉是玉米、小麦和水稻等驯化谷物产量的主要决定因素，其高热量含量对于人类和动物的消费至关重要。 它也是非食品工业中的重要商品，其功能取决于葡萄糖残基在严格定义的半晶体结构中的组织，但人们对其组装仍知之甚少。 淀粉代谢支撑着植物遗传和代谢决策之间的相互作用，决定了包括开花和种子产生在内的发育过程的时间和启动。 它的动员对于植物的生长至关重要，我们开始认识到影响其在来源组织中的合成和结构会对生产力产生重大影响。 我的研究重点是了解：1）负责淀粉合成和结构的生化和分子机制2）植物如何分配资源以支持生长和发育。 我们已经证明，参与淀粉生物合成的几种酶形成异聚复合物，它们以物理方式协同作用，产生淀粉的主要成分支链淀粉。 这些复合物的组装由位于发育种子的淀粉​​体或制造淀粉的叶子的叶绿体内的蛋白激酶在翻译后控制。 最近我们发现，通过改变模型植物拟南芥中支链淀粉合成所涉及的淀粉分支酶的特定亚型，不仅可以改变支链淀粉的结构，而且可以在生物量和种子产量方面产生深刻的积极变化提高油料作物产量的新机遇。 我们还鉴定了全局代谢调节因子 SnRK1 的非催化亚基，它对碳水化合物的利用具有显着影响，并整合了有机酸、脂质的代谢和硝酸盐的吸收。 因此，该提案的主要目标是 1) 了解翻译后机制如何影响所产生的淀粉的数量和结构 2) 确定支持有效利用淀粉促进生长和发育的分子、生理和生化决定因素 3) 研究全球新陈代谢调节剂在控制资源和营养物质分配以促进生长方面的作用。 我们已做好准备提供此类知识，为作物生物工程提供机会，以应对全球人口迅速增长的挑战。