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) (www.ars-grin.gov/).
