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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=650187
• 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：直链淀粉，它的合成只需要一个单一的酶；以及更高分支的支链淀粉，它需要至少10个基因产物的协调活性。淀粉是玉米、小麦和大米等驯化谷物产量的主要决定因素，这些谷物的高热量含量对人类和动物的消费都是至关重要的。它也是非食品行业的一种重要商品，在非食品行业，其功能依赖于严格定义的半结晶结构中葡萄糖残基的组织，但对其组装仍知之甚少。淀粉的代谢是植物遗传和代谢决策之间相互作用的基础，决定着包括开花和种子生产在内的发育过程的时间和开始。它的动员对植物的生长至关重要，我们开始了解到，影响其在源组织中的合成和结构可以对生产力产生重大影响。我的研究主要集中在以下几个方面：1)影响淀粉合成和构型的生化和分子机制；2)植物如何分配资源以支持生长发育。*我们已经证明了参与淀粉生物合成的几种酶形成了异构体复合体，它们在物理上和协同作用下共同产生淀粉的主要成分支链淀粉。这些复合体的组装是由翻译后的蛋白激酶控制的，这些蛋白激酶位于发育中的种子的淀粉体或制造淀粉的叶片的叶绿体中。最近我们发现，通过改变模式植物拟南芥中参与支链淀粉合成的淀粉分支酶的特定亚型，不仅有可能改变支链淀粉的结构，而且在生物量和种子生产方面也有深刻的积极变化，为提高油料作物的产量提供了新的机会。我们还发现了全球新陈代谢调节因子SnRK1的一个非催化亚基，它对碳水化合物的利用有重大影响，并整合了有机酸、脂肪的代谢和硝酸盐的吸收。因此，这一建议的主要目标是：1)了解翻译后机制如何影响淀粉的产量和结构；2)确定支撑淀粉有效利用生长和发育的分子、生理和生化决定因素；3)研究全球新陈代谢调节因子在控制资源和营养分配到生长中的作用。我们已经做好准备，提供这些知识，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。