RESEARCH-PGR: Developing novel strategies to enhance the tolerance of crops to a combination of drought and heat stress.

干旱胁迫期间发生的热浪对农业生产和产量造成毁灭性影响。例如，1980年、1988年、2000年、2003年和2008年夏季发生的干旱和高温共同导致的产量损失估计分别为33亿美元、44亿美元、76亿美元、7亿美元和86亿美元。由于全球变暖及其对气候变化的影响在很大程度上是不可抗拒的，预计未来几年干旱和高温胁迫的强度和频率将增加，因此培育提高对干旱和高温胁迫组合的耐受性的作物对现代农业和粮食可持续发展至关重要。干旱和高温胁迫期间产量损失的关键是开花和受精等过程，这些过程对这些条件特别敏感，而且对几乎所有谷物和豆类的产量都非常重要。本项目的重点是高温、干旱以及干旱和高温组合对大豆开花、受精和种子生产的影响。利用一系列实验工具，可以确定提高大豆对这些胁迫条件的耐受性所必需的基因和蛋白质。这些蛋白质和基因将使育种者能够开发出能够抵抗当前和未来环境恶劣条件的新的基因类型，并确保未来几年安全和可持续的大豆种子生产。大豆、玉米、水稻和小麦等许多不同作物在生殖生长阶段发生的干旱和高温胁迫相结合，对产量造成了毁灭性的影响。在大豆中，人们已经做出了相当大的努力来培育在干旱或高温胁迫条件下提高产量的基因型。然而，这些基因型在干旱和高温联合胁迫条件下的表现大多尚不清楚。此外，尽管过去的研究主要集中在非生物胁迫对花粉活力的影响上，但最近的研究结果表明，干旱和高温胁迫的组合对花粉萌发后发生的生殖过程具有独特的影响。本文建议利用干旱或高温胁迫条件下种子产量发生变化的独特的大豆基因型集合来识别在干旱和高温条件下影响种子产量的基因和基因网络。利用田间和生长室内研究干旱和高温组合对不同类型大豆生殖组织和产量的影响，结合显微切割技术、RNA测序和机器学习驱动的网络分析工具，将识别在组合胁迫条件下影响生殖过程的基因和基因网络。这些基因/基因网络的功能将通过在转基因大豆植株中对它们的表达进行遗传修改来验证，总体目标是提高在干旱和高温组合条件下生长的大豆植株的产量。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Heat waves occurring during periods of drought stress have a devastating impact on agricultural production and yield. A combination of drought and heat stress occurring during the summers of 1980, 1988, 2000, 2003 and 2008, for example, resulted in yield losses estimated in 33, 44, 7.6, 7 and 8.6 billion dollars, respectively. Because episodes of drought and heat stress are expected to increase in intensity and frequency in the coming years, due to the largely unopposed process of global warming and its consequential impacts on climate change, breeding crops for enhanced tolerance to a combination of drought and heat stress is of the utmost importance for modern agriculture and food sustainability. Crucial for yield loss during episodes of drought and heat stress are processes such as flowering and fertilization that are especially sensitive to these conditions, as well as highly important for yield production in almost all cereals and legumes. In this project the focus is on the impact of heat, drought, and drought and heat combination on flowering, fertilization, and seed production of soybean. Using a combination of experimental tools, genes and proteins that are essential for enhancing the tolerance of soybean to these stressful conditions will be identified. These proteins and genes will enable breeders to develop new genotypes that will resist the harsh conditions of our current and future environment and ensure a secure and sustainable soybean seed production for years to come.A combination of drought and heat stress occurring during the reproductive growth phase of many different crops, such as soybean, corn, rice, and wheat, has a devastating impact on yield. In soybean, a considerable effort has been made to develop genotypes with enhanced yield production under conditions of drought or heat stress. However, how these genotypes perform under conditions of drought and heat stress combination is mostly unknown. Moreover, although past research has focused on the impact of abiotic stress on pollen viability, recent findings reveal that the combination of drought and heat stress has a unique impact on reproductive processes that occur post pollen germination. Here, it is proposed to utilize a unique collection of soybean genotypes with altered seed production under conditions of drought or heat stress conditions to identify genes and gene networks impacting seed production under a combination of drought and heat stress. Using a combination of field and growth chamber studies focused on the effect of drought and heat stress combination on reproductive tissues and yield of different soybean genotypes, coupled with microdissection techniques, RNA sequencing and machine learning-driven network analysis tools, genes and gene networks that impact reproductive processes under conditions of stress combination will be identified. The function of these genes/gene networks will be validated by genetically modifying their expression in transgenic soybean plants with the overall goal of enhancing yield of soybean plants grown under conditions of drought and heat stress combination.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.