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.

谷物产量的增加对人类来说至关重要，这项建议解决了影响谷物产量和生存能力的因素。光合作用电子传递(PET)提供能量来固定叶片中的碳，这些碳被运输以支持籽粒灌浆。谷类的花器官也是绿色的，PET在种子发育中对产量和活力特别重要，但人们对此知之甚少。我们已经开发了技术和遗传工具来帮助填补这一知识空白。为什么是大麦种子？：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，这种谷物品种非常有效地将叶片光合作用转化为发育中的种子。谷类花穗中的光合作用过程对高产也很重要，尤其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，从而进一步提高粮食产量。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6个基因组拷贝)，这使得它作为遗传工具很难使用。大麦是北欧第三大种植谷物，虽然与小麦有密切的亲缘关系，但由于它是二倍体(每个细胞两个基因组拷贝)，所以在遗传上更容易驯化。因此，有关大麦的知识也可以为小麦育种计划提供信息，因此研究大麦的工作既迅速又有很大的影响。为什么是光合作用的电子传递？光合作用电子传递(PET)为固定CO2提供能量，在谷类植物叶片中被广泛理解。相比之下，我们对PET在种子发育过程中的了解要少得多，这对种子的生存能力和产量也很重要。尽管没有与大气有效地交换O2或CO2，但正在发育的种子在发育过程中组装和分解了PET的设备。人们提出了两个假说来解释这一现象：1)PET产生O2，防止种子缺氧，并使呼吸支持籽粒灌浆；2)PET产生活性氧(ROS)，触发激素信号通路，控制种子发育和以后的幼苗生长。种子中的光合作用电子传递与叶片不同吗？我们先前发现，TROL是一种PET蛋白，在模式植物拟南芥的逆境耐受性中起重要作用。我们通过敲除大麦中这种蛋白质的两个基因，研究了这一发现是否具有农学意义。令人惊讶的是，TROL的丢失并没有影响叶片中的PET，但确实扰乱了种子发育中的PET。与野生型相比，突变体的籽粒产量和种子活力总体上也较差。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正在发育的种子中的PET与叶片中的PET的不同之处，并确定对PET种子特别重要的途径和成分。实验建议：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，密度高，而且散射光。我们已经开发出了准确做到这一点的方法，我们的初步结果已经表明，叶和种子PET之间存在显著差异。我们将试图通过比较叶片和种子中PET装置的组成和结构来了解这些差异的基础。已经产生的TROL基因突变体将与其他突变体相互补充，以检验不同的PET途径如何对种子产量和活力做出贡献。最后，我们将确定是否可以通过在种子发育的特定时间点刺激依赖TROL的PET途径来提高种子产量和活力。通过了解调节谷物灌浆和生存能力的触发因素，我们希望最终确定如何使谷物产量不受环境变化的影响。