RESEARCH-PGR: Genomic analysis of heat stress tolerance during tomato pollination

由于花粉管生长的热敏感性，开花和授粉期间的高温会导致显著的果实损失。不同番茄品种对花粉管生长的热敏性存在显著差异。利用这种自然产生的品种，该项目试图确定适应的分子基础，以减轻作物繁殖过程中高温胁迫对产量造成的破坏后果。目标是开发新的番茄品种，这些品种具有可育性，并在高温下继续结出果实。该项目将在基因组科学、发育生物学和遗传变异的计算分析方面培训本科生、研究生和博士后研究员。该项目将建立在其中一名团队成员开发的成功外展计划的基础上。该程序已被用于向1000多名9年级学生讲授植物遗传学、植物育种和基因工程科学，并针对温度胁迫对番茄繁殖的影响进行了定制。假设耐热番茄品种表达的花粉管热应激反应在温度敏感品种中不存在或减弱，耐热雌蕊缓冲热胁迫并促进花粉管生长。为了确定番茄耐热性的分子机制，将测定耐热性和热敏性番茄品种的花粉管和雌蕊中伴随着热胁迫的转录变化。将进行花粉管耐热性的单倍体选择定位，然后进行实验测试，确定的候选基因是否与耐热性有因果关系。该项目将生成可访问和随时可用的社区数据库，1)详细说明生殖基因表达对高温的反应，2)登记数百个番茄基因组的遗传变异，以便能够分析热胁迫适应和其他特征。该项目将定义伴随着花粉管和雌蕊中的热胁迫而发生的转录变化(目标1)，导致花粉管耐热性的遗传变异(目标2和3)，以及使用反向遗传学的单个耐热基因的功能(目标4)。该奖项反映了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。

High temperatures during flowering and pollination can result in significant fruit losses, because of heat sensitivity of pollen tube growth. Different tomato varieties show significant differences in heat sensitivity of pollen tube growth. Making use of this naturally occurring variety, this project seeks to identify the molecular basis of adaptations that mitigate the yield-damaging consequences of heat stress during crop reproduction. The goal is to develop new tomato varieties that are fertile and continue to produce fruits at high temperature. This project will train undergraduate and graduate students and postdoctoral fellows in genome science, developmental biology, and computational analysis of genetic variation. The project will build on the successful outreach program developed by one of the team members. This program has been used to teach plant genetics and the science of plant breeding and genetic engineering to more than 1000 9th grade students, tailoring it to focus on the effects of temperature stress on tomato reproduction.It is hypothesized that thermotolerant tomato varieties express a pollen tube heat stress response that is either absent or diminished in thermosensitive cultivars and that the thermotolerant pistil buffers heat stress and facilitates pollen tube growth. To identify the molecular mechanisms of thermotolerance in tomato, transcription changes that accompany heat stress in pollen tubes and pistil will be measured in heat tolerant and heat sensitive tomato varieties. Haploid selection mapping of pollen tube heat tolerance will be performed, followed by experimental tests whether identified candidate genes are causally related to heat tolerance. This project will generate accessible and readily available community databases 1) detailing reproductive gene expression responses to elevated temperature and 2) registering genetic variants across hundreds of tomato genomes to enable analysis of heat stress adaptation and other traits. The project will define the transcriptional changes that accompany heat stress in the pollen tube and pistil (Aim 1), genetic variation responsible for pollen tube thermotolerance (Aims 2 and 3), and the functions of individual thermotolerance genes using reverse genetics (Aim 4).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.