Genome-Wide Association Study for Drought and Agronomic Traits in a Multi-Parent Advanced Generation Intercross (MAGIC) Population of Sorghum.

Drought tolerance and grain yield are important traits in sorghum [Sorghum bicolor (L.) Moench], comprehensively studied and yet their genetic bases remain elusive. We conducted a genome-wide association study (GWAS) in a panel of 200 multiparent advanced generation inter-cross (MAGIC) inbreeds to identify genomic regions associated with drought tolerance, grain yield (GY), yield stability (YS) and 100 seed weight (HSW). Genotypes were evaluated for yield traits across multiple environments and further assessed for drought-like response under salt desiccation stress. GWAS using a 79K SNPs, generated via a high throughput genotyping-by-sequencing (GBS) platform identified four genomic regions associated with drought tolerance. These regions harbored fourteen candidate genes, orthologous to Arabidopsis thaliana, Mize (Zea may) and Rice (Oriza sativa) with functional annotations depicted in abiotic stress defenses. Additionally, we detected three suggestive association signals each for GY, YS and HSW. The genes proximal to these regions were previously shown by Maize transcriptomic analysis to be involved in phytohormone pathway, carbohydrate metabolism, sugar transport and stress defense. These pathways/biological processes are known to either directly or indirectly influence grain yield traits in crop plants. Further analysis detected 22 GY and 9 HSW genomic regions that were environment sensitive, revealing the presence of gene-environment interaction. The results of this study added more insights into the nature of genetic variations governing drought tolerance and grain yield traits in sorghum.