Reduced Stomatal Density Wheat: New Prospects for Drought and Pathogen Resistance

气孔是叶子表面的微小气孔，它允许植物和大气之间进行气体交换。它们对光合作用至关重要，但水蒸气会通过气孔流失，它们为破坏性疾病提供了一个入口。当水分有限时，气孔调节以防止水分流失，但它们永远不能完全关闭。我们已经用试验植物拟南芥表明，减少气孔数量可以通过减少蒸腾作用导致的水分损失来提高植物的抗旱性。由于二氧化碳浓度上升，这些植物的光合作用几乎没有减少。我们想把这个策略应用到小麦上，这样我们就可以测试减少气孔数量是否可以提高作物的耐旱性，这是世界上许多地方产量的主要限制。我们已经培育出了气孔数量遗传减少的小麦植株，并提议测试在干旱条件下种植这些植物是否能提高收获的谷物总产量。我们将检查我们在气孔数量和水分损失方面所做的改变是否对根系吸收重要矿物质（如磷酸盐和硝酸盐）产生有害影响。此外，我们将分析小麦谷物，以确保对人类饮食重要的营养水平没有受到影响。气孔是导致英国小麦作物重大损失的几种重要真菌疾病的唯一切入点。我们已经证明，除了更抗旱之外，我们的拟南芥试验植物气孔数量减少，还有减少致病微生物进入的额外好处。因此，该项目的一个重要组成部分将是测试我们鉴定的气孔数量减少的小麦植株是否对这些真菌疾病具有增强的抗性。如果是这样，该性状具有保护作物产量的潜力，并可转移到许多由气孔进入的疾病感染的作物上。研究植物抗病性的实验将由位于剑桥的国家农业植物学研究所（NIAB）进行。在谢菲尔德，我们有在不同环境条件下种植植物的优良设施。我们将能够测试我们的小麦在不久的将来预计会出现的二氧化碳浓度升高的情况下是否继续表现良好。这些实验将在转基因（GM）植物上进行，但我们也建议通过非转基因技术分离小麦中已知参与气孔发育的基因变异，以便我们可以将这些基因纳入我们的研究并测试它们对干旱和病原体的抗性。我们希望可持续农业研究与创新俱乐部（SARIC）的一个商业成员愿意支持我们的工作，通过将一种新的耐旱小麦品种商业化。

Stomata are microscopic pores on the surface of leaves that allow gas exchange between plants and the atmosphere. They are crucial for photosynthesis, but water vapour is lost through stomata, and they provide an entry point for damaging diseases. When water is limiting, the stomatal pores adjust to prevent water loss but they can never completely close. We have shown with the test plant Arabidopsis that reducing the number of stomata can improve plant drought resistance by reducing water loss through transpiration. Because of rising carbon dioxide levels these plants showed little or no reduction in photosynthesis. We would like to apply this strategy to wheat so that we can test whether reducing stomatal numbers could improve crop drought tolerance, a major limitation to yield in many parts of the world. We have already generated wheat plants with genetically reduced stomatal numbers, and propose to test whether growing these under drought conditions can improve the total yield of grain harvested. We will check that the alterations we have made in stomatal number and water loss have not had a detrimental effect on the uptake of important minerals, such as phosphate and nitrate by the roots. In addition, we will analyze the wheat grain to ensure that the level of nutrients important for the human diet have not been affected. Stomata are the only entry point for several important fungal diseases that cause major losses of wheat crops in the UK. We have shown that in addition to being more drought resistant, our Arabidopsis test plants with reduced stomatal number, have the added benefit of reduced entry of disease causing microbes. Therefore an important part of this project will be to test whether the wheat plants that we have identified with reduced stomatal number have enhanced resistance to these fungal diseases. If so, this trait has the potential to protect crop yields, and could be transferred to many crops which are infected by diseases entering through stomata. The experiments to look plant disease tolerance will be carried out by the National Institute of Agricultural Botany (NIAB) in Cambridge.In Sheffield we have excellent facilities for growing plants under different environmental conditions. We will be able to test whether our wheat continue to perform as well when grown at the raised carbon dioxide levels predicted to occur in the near future. These experiments will be performed on genetically modified (GM) plants but we also propose to isolate wheat variants in genes that are known to be involved in stomatal development through a non-GM technique, so that we can include these in our studies and test them for drought and pathogen resistance. We hope that one of the commercial members of the Sustainable Agriculture Research & Innovation Club (SARIC) will want to support our work through to commercialising a new drought tolerant wheat variety.