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

拟议的研究通过产生对开发在授粉过程中具有改善的耐热性的作物植物具有重要意义的基础科学见解，解决了一个关键的全球粮食安全挑战。预测表明，到2050年，全世界的粮食产量必须增加70%，才能养活预期的90亿世界人口。温度胁迫是世界各地作物损失的主要原因，花粉不育是最重要的根本原因之一。 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破坏繁殖成功。了解这种脆弱性意义重大，因为世界上大部分粮食供应来自依赖授粉的种子作物。拟议研究的变革潜力来自于开创性地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。 通过与内华达州大学（里诺）和以色列巴伊兰大学这两个机构合作，共同指导研究生，将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，即提高干旱土地环境下的农业生产力。长期目标是了解不同的植物细胞如何科普非生物胁迫，并利用这些知识提高作物生产力。这里的重点是花粉如何在有限的时间内感知和响应热胁迫，在此期间它们必须生长，定位胚珠，并排出雄配子体使卵细胞受精。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）触发转录组中独特的花粉特异性变化的信号通路。Specific Aim 1采用花粉传递试验对80多个候选基因进行遗传测试，以确定其在热胁迫期间增加或降低花粉育性的潜力。目的2是鉴定转录组中与ROS细胞水平变化相关的热应激依赖性变化。该目的将涉及使用荧光激活的细胞分选仪来分离热应激花粉的亚群，所述亚群显示高或低水平的ROS，从而使得能够在两个细胞亚群之间进行转录组比较，所述两个细胞亚群显示它们对热的响应的差异。 目的3是使用定量蛋白质组学策略来鉴定翻译后修饰中的热应激依赖性变化，例如转录因子磷酸化的变化。一个统一的目标是确定候选基因或翻译后修饰，可以操纵，以提高花粉的耐热性。

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.