(1100-18) Genetic analysis of leaf functional and eco-physiological traits to optimize water use efficiency in sorghum under seasonal drought conditions
Postdoc Michigan State University EAST LANSING, Michigan
Body of Abstract: Seasonal drought is expected to reduce soil water availability in many agricultural production areas globally, requiring a deeper understanding of how drought affects leaf functional and eco-physiological traits. Leaf developmental traits and stomatal features are the basic leaf functional traits that facilitate CO2 uptake for photosynthesis while minimizing water loss. Sorghum is a C4 plant adapted to moderate drought stress, and its extensive natural variation in photosynthetic traits can be used to develop stress-tolerant cultivars. The goal of this study was to understand the relationship between leaf functional traits and eco-physiological traits by combining phenomic, physiological, and genetic approaches. We monitored periodic rain-fed and rain-deprived conditions in the sorghum field and evaluated stress responses using stomatal gas conductance and relative water content, both of which were significantly reduced under rain-deprived conditions. Then, we phenotyped stomata features (density, index, length, width, pore area, etc.), and leaf developmental traits, particularly specific leaf area, and leaf thickness, by simultaneously evaluating gas exchange and water use efficiency across natural variations present in sorghum accessions. The phenotypic data was integrated with genomic data and genome-wide association studies was performed to discover genes/genomic regions that control leaf functional and eco-physiological traits under natural conditions. Several candidate genes were identified with predicted functions related to stomata density and distribution, carotenoids, phytohormones, thioredoxin, components of PSI and PSII, and antioxidants. Then, a range of accessions based on the REF and ALT alleles obtained from marker-trait analysis (SNP for stomata density, net photosynthesis rate and water-use efficiency) were utilized to model stomatal conductance response under different eco-physiological conditions. Overall, our findings contribute to our understanding of sorghum's natural variation and genetic control of leaf functional and eco-physiological traits in response to drought, with the ultimate goal of improving its adaptation and productivity under water stress conditions.