NSF-IOS-BSF: Collaborative Research US/Israel: Transcriptome and post-translational regulation of heat stress tolerance in pollen

这项拟议的研究通过产生基本的科学见解来解决世界范围内的一个关键的粮食安全挑战，这些科学见解对于开发授粉期间具有更好的耐热胁迫能力的作物非常重要。到2050年，预测表明，全球粮食产量必须增加70%，才能养活预计90亿世界人口。温度胁迫是世界各地农作物损失的主要原因，而花粉不育是最重要的潜在原因之一。植物繁殖过程中的受精对冷热温度高度敏感，即使是一个炎热的白天或寒冷的夜晚也有可能扰乱繁殖成功。了解这一脆弱性意义重大，因为世界上大部分粮食供应来自依赖授粉的种子作物。这项拟议研究的变革潜力来自于率先使用花粉作为模型系统，以获得对植物耐热性机制的分子和遗传见解。将通过与内华达大学(Reno)和以色列巴伊兰大学这两个机构合作，共同指导研究生，为更广泛的影响作出更多贡献。这两个机构都有一个共同的目标，那就是提高干旱土地环境中的农业生产率。长期目标是了解不同的植物细胞如何应对非生物胁迫，并利用这些知识来提高作物生产率。这里的重点是在一段有限的时间内，花粉如何感知和响应高温胁迫，在这段时间内，它们必须生长、定位胚珠并释放雄配子体以使卵细胞受精。指导这项研究的中心假设是，花粉中的保护性热应激反应涉及利用钙和ROS(活性氧物种)在转录组中触发独特的花粉特有变化的信号通路。特殊目的1使用花粉传递试验对80多个候选基因进行遗传测试，以确定它们在高温胁迫期间增加或降低花粉可育性的潜力。目标2是确定转录组中与管理或响应细胞内ROS水平的变化相关的热应激依赖的变化。这一目标将涉及使用荧光激活的细胞分选器来分离热胁迫下显示高或低水平ROS的花粉亚群，从而能够在两个亚群细胞之间进行转录组比较，显示它们对热的反应不同。目标3是使用定量蛋白质组学策略来识别翻译后修饰中依赖于热应激的变化，例如转录因子磷酸化的变化。一个统一的目标是识别候选基因或翻译后修饰，这些基因或修饰可以被操纵来提高花粉的耐热性。

The proposed research address a critical world-wide food security challenge by generating fundamental scientific insights of importance to developing crop plants with improved heat-stress tolerance during pollination. By the year 2050, projections indicate that world-wide food production must increase by 70% in order to feed an expected world population of 9 billion people. Temperature stress is a major contributor to crop loss around the world, with pollen infertility being one of the most important underlying causes. Fertilization during plant reproduction is highly sensitive to hot and cold temperatures, with even a single hot day or cold night carrying the potential to disrupt reproductive success. Understanding this vulnerability is significant because most of the world's food supply is derived from seed crops that depend on pollination. The transformative potential of the proposed research is derived from pioneering the use of pollen as a model system to gain molecular and genetic insights into thermo-tolerance mechanisms in plants. Additional contributions to broader impacts will occur through co-mentoring graduate students in a collaboration involving two institutions, the University of Nevada (Reno) and Bar-Ilan University, Israel. Both institutions share a common goal of increasing agricultural productivity in arid land environments.The long-term goal is to understand how different plant cells cope with abiotic stress, and to use that knowledge to improve crop productivity. The focus here is on how pollen sense and respond to heat stress during a limited period of time in which they must grow, locate ovules, and discharge male gametophytes to fertilize egg cells. The central hypothesis guiding the proposed research is that a protective heat-stress response in pollen involves signaling pathways that utilize calcium and ROS (reactive oxygen species) to trigger unique pollen-specific changes in the transcriptome. Specific Aim 1 employs a pollen transmission assay to genetically test more than 80 candidate genes for their potential to increase or decrease pollen fertility during a heat stress. Aim 2 is to identify heat-stress dependent changes in the transcriptome that are correlated to managing or responding to changes in cellular levels of ROS. This aim will involve using a fluorescence-activated cell sorter to isolate sub-populations of heat-stressed pollen that show either high or low levels of ROS, and thereby enable a transcriptome comparison to be made between two subpopulations of cells showing differences in their response to heat. Aim 3 is to use a quantitative proteomics strategy to identify heat-stress dependent changes in post-translational modifications, such as changes in phosphorylation of transcription factors. A unifying goal is to identify candidate genes or post-translational modifications that can be manipulated to improve heat-stress tolerance in pollen.