Connecting grain yield and viability with photosynthetic electron transport in developing seeds

将谷物产量和活力与种子发育中的光合电子传递联系起来

• 批准号: BB/X002063/1
• 负责人: Guy Hanke
• 金额: $ 64.93万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX002063%2F1
• 关键词: Connecting; grain; yield; viability; photosynthetic

It is critical for humanity that cereal crop yields increase, and this proposal addresses factors that contribute to grain yield and viability. Photosynthetic electron transport (PET) provides the energy to fix carbon in leaves, which is transported to support grain filling. Cereal floral organs are also green, and PET in developing seeds is particularly important for yield and viability, but poorly understood. We have developed techniques and genetic tools to help fill this knowledge gap. Why barley seeds?: In the 1950s and 60s the "Green Revolution" saved millions from starvation by developing high yield cereal varieties, that were extremely efficient at transferring leaf photosynthate into developing seeds. Photosynthetic processes in cereal flower spikes are also important for high yield, and in particular the role of green tissues in developing cereal seeds remains poorly understood. Investigating this could inform breeding programs leading to further increases in grain yield. Studying barley is one of the fastest routes to improving cereal yield: In the UK and continental Europe, wheat is still the dominant cereal crop, but it is hexaploid (6 genome copies per cell) making it unwieldy as a genetic tool. Barley is the third most farmed cereal in Northern Europe and although closely related to wheat, is more genetically tractable as it is diploid (two genome copies per cell). Knowledge about barley can therefore also inform wheat breading programs, so work on barley is both rapid and high impact. Why photosynthetic electron transport? Photosynthetic electron transport (PET) provides the energy for CO2 fixation, and is well understood in cereal leaves. By contrast, we know much less about PET in developing seeds, which is also important for viability and yield. Despite not efficiently exchanging O2 or CO2 with the atmosphere, the developing seed assembles and breaks down the apparatus for PET during its development. Two hypotheses have been proposed to explain this: 1) PET produces O2, preventing hypoxia in the seed and enabling respiration to support grain filling; 2) PET produces reactive oxygen species (ROS), which trigger hormone signaling pathways that control seed development and later seedling growth.Is photosynthetic electron transport in seeds different from leaves? We previously found that TROL, a PET protein, is important for stress tolerance in Arabidopsis, a model plant. We investigated whether this finding could have agronomic importance by knocking out the 2 genes for this protein in barley. Surprisingly, loss of TROL did not affect PET in leaves, but did disrupt it in developing seeds. In comparison to wild type, the mutants also showed poor grain yield, and poor seed viability overall. In the work proposed here we will use these plants as a tool to understand how PET in the developing seed differs from PET in the leaf, and identify pathways and components that are uniquely important to seed PET. Experiments proposed: Techniques to accurately measure PET require light transmittance through tissue, which is challenging in developing cereal seeds, as they are starchy, dense and scatter light. We have developed methods to accurately do this, and our preliminary results already indicate significant differences between leaf and seed PET. We will try to understand the basis of these differences by comparing the composition and structure of the PET apparatus in leaves and seeds. The TROL gene mutants already generated will be complimented with others to examine how different PET pathways contribute to seed yield and viability. Finally, we will determine whether seed yield and viability can be improved by stimulating TROL-dependent PET pathways at specific points in seed development. By understanding the triggers that regulate grain filling and viability, we hope to eventually identify ways in which cereal yields can be future-proofed against a changing environment.

谷物作物产量的增加对人类至关重要，该提案解决了有助于谷物产量和生存能力的因素。光合电子传输（PET）提供能量来固定叶子中的碳，这些能量被传输以支持谷物灌浆。谷物花器官也是绿色的，PET 在种子发育过程中对于产量和活力特别重要，但人们对此知之甚少。我们开发了技术和遗传工具来帮助填补这一知识空白。为什么选择大麦种子？：在 20 世纪 50 年代和 60 年代，“绿色革命”通过开发高产谷物品种使数百万人免于饥饿，这些品种在将叶子光合作用转化为正在发育的种子方面非常有效。谷类花穗中的光合作用过程对于高产也很重要，特别是绿色组织在谷类种子发育中的作用仍然知之甚少。研究这一点可以为育种计划提供信息，从而进一步提高谷物产量。研究大麦是提高谷物产量的最快途径之一：在英国和欧洲大陆，小麦仍然是主要的谷物作物，但它是六倍体（每个细胞有 6 个基因组拷贝），使其无法作为遗传工具使用。大麦是北欧第三大种植谷物，虽然与小麦密切相关，但由于它是二倍体（每个细胞有两个基因组拷贝），因此在遗传上更容易处理。因此，有关大麦的知识也可以为小麦面包屑计划提供信息，因此有关大麦的工作既迅速又具有高影响力。为什么要进行光合作用电子传递？光合电子传递（PET）为二氧化碳固定提供能量，这一点在谷物叶子中得到了很好的理解。相比之下，我们对 PET 在种子发育过程中的了解要少得多，而这对于活力和产量也很重要。尽管不能有效地与大气交换 O2 或 CO2，但发育中的种子在发育过程中会组装和分解 PET 装置。人们提出了两个假设来解释这一点：1）PET 产生 O2，防止种子缺氧并进行呼吸以支持籽粒灌浆； 2) PET 产生活性氧 (ROS)，从而触发控制种子发育和后期幼苗生长的激素信号通路。种子中的光合电子传递与叶子不同吗？我们之前发现 TROL（一种 PET 蛋白）对于模式植物拟南芥的胁迫耐受性非常重要。我们通过敲除大麦中该蛋白质的 2 个基因来研究这一发现是否具有农艺重要性。令人惊讶的是，TROL 的缺失并没有影响叶子中的 PET，但确实破坏了种子发育过程中的 PET。与野生型相比，突变体还表现出较差的谷物产量和较差的种子活力。在这里提出的工作中，我们将使用这些植物作为工具来了解发育中的种子中的 PET 与叶子中的 PET 有何不同，并确定对种子 PET 特别重要的途径和成分。提出的实验：精确测量 PET 的技术需要通过组织的透光率，这在开发谷物种子方面具有挑战性，因为它们含有淀粉、致密且散射光。我们已经开发出准确做到这一点的方法，并且我们的初步结果已经表明叶子和种子 PET 之间存在显着差异。我们将尝试通过比较叶子和种子中 PET 设备的组成和结构来了解这些差异的基础。已经生成的 TROL 基因突变体将与其他基因突变体一起使用，以检查不同的 PET 途径如何促进种子产量和活力。最后，我们将确定是否可以通过在种子发育的特定点刺激 TROL 依赖性 PET 途径来提高种子产量和活力。通过了解调节谷物灌浆和活力的触发因素，我们希望最终找到使谷物产量能够适应未来环境变化的方法。