CAREER: Photoprotection for Tolerance to Abiotic Stress: Discovery through Natural Genetic Variation

光合作用是维持地球生命的基本生化过程，需要光能。任何环境压力，如寒冷，干旱或高温，都会限制固定的二氧化碳量，并触发光保护机制，以消散或避免吸收可能对细胞和整个植物造成损害的多余能量。光保护的生理和遗传方面已经在模式物种中进行了研究，但还没有研究光保护作为作物物种非生物胁迫耐受性的有用和可改进的机制。考虑到非生物胁迫是农业系统产量损失的主要原因，并且气候变化将产生更加极端的环境条件，利用新的非生物胁迫机制，如光保护，可能对作物生产力产生重大影响，从而对我们社会的繁荣产生重大影响。该项目的目标是利用高粱（一种重要的商业作物）的自然遗传变异，发现影响植物在压力条件下科普过多能量的能力的基因/分子标记。本项目的具体目标包括：1）确定最大化光保护反应的干旱和寒冷实验条件; 2）通过连锁不平衡（LD）作图检测光保护候选基因与光合作用和荧光的关联; 3）发现与光保护变异相关的新基因/标记;和4）鉴定候选基因、功能多态性并确定与胁迫下较高的光保护能力相关的等位基因变体的表达水平。该项目的成果包括与上级光保护能力相关的基因/标记和等位基因变体，这些基因的功能多态性和表达谱，以及可以在多种环境条件下进行测试并在育种计划中利用的分子标记。该项目还将为一名博士生和一名本科生提供研究培训和指导。 关于对公众的宣传，该项目将为Meta！Blast是一款实时3D动作冒险视频游戏，旨在让学生参与复杂生物系统的学习过程。“光保护”是对现有单元的补充，将侧重于光保护及其对社会的影响。这个游戏将被高中教师用于生物课程，也将用于爱荷华州州立大学（ISU）的本科课程。 此外，该项目还将分别在一年两次的爱荷华州农场进步展和ISU研究和示范农场上提供示范和推广介绍。由于参加这些活动的人数众多、他们在农业生产系统中的作用以及因此对社会的影响，这些向公众传播该项目产生的知识的机会具有独特的价值。 该项目中使用的所有菌种都可以通过USDA-ARS国家遗传资源保护（NCGRP）免费获得。 所有序列数据将保存在NCBI GenBank dbSNP和GSS数据库中。 所有表型数据将长期保存在USDA-ARS种质资源信息网（GRIN）（http：//www.ars-grin.gov/）。

Photosynthesis, the fundamental biochemical process sustaining life in this planet, requires light energy. Any environmental stress such as cold, drought or heat will limit the amount of fixed CO2, and trigger photoprotection mechanisms to dissipate or avoid absorption of excess energy that might cause damage to cells and the plant as a whole. The physiological and genetic aspects of photoprotection have been studied in model species but there has been no investigation of photoprotection as a useful and improvable mechanism of abiotic stress tolerance in crop species. Considering that abiotic stresses are the main cause of yield loss in agricultural systems, and that climate change will generate even more extreme environmental conditions, the utilization of a novel abiotic stress mechanism such as photoprotection could have a significant impact on crop productivity and thus on the prosperity of our society. The goal of this project is to discover genes/molecular markers affecting the plant's capacity to cope with excessive energy under stress conditions, using natural genetic variation in sorghum, a commercially important crop. This project includes the following specific aims: 1) to determine the drought and cold experimental conditions that would maximize the photoprotection response; 2) to test the association of photoprotection candidate genes with photosynthesis and fluorescence by Linkage Disequilibrium (LD) mapping; 3) to discover novel genes/markers associated with variation in photoprotection; and 4) to identify candidate genes, functional polymorphisms and determine expression levels of allelic variants associated with higher photoprotective capacity under stress. The outcomes of this project include genes/markers and allelic variants associated with superior photoprotective capacity, the functional polymorphisms and expression profiles of those genes, and molecular markers that could be tested under multiple environmental conditions and exploited in breeding programs. The project will also provide research training and mentoring for one PhD and one undergraduate student. With regard to outreach to the general public, the project will develop a new module for Meta!Blast, a real-time 3D action-adventure video game designed to engage students in the learning process of complex biological systems. "Photoprotection" complements current modules and will focus on photoprotection and its effects on society. This game will be utilized by high school teachers in biology courses but also in undergraduate courses at Iowa State University (ISU). In addition, the project will provide demonstrations and extension presentations at the biannual Iowa Farm Progress Show and the ISU Research and Demonstration Farms, respectively. These opportunities to disseminate knowledge generated in this project to the general public are uniquely valuable because of the number of people attending those events, their roles on agricultural production systems and therefore their impact on society. All germplasms used in this project are freely available through the USDA-ARS National Genetic Resources Preservation (NCGRP). All sequence data will be deposited in the NCBI GenBank dbSNP and GSS databases. All phenotypic data will be deposited long-term at the USDA-ARS Germplasm Resources Information Network (GRIN) (http://www.ars-grin.gov/).