Genome Wide Association Study for Nine Plant Architecture Traits in Sorghum bicolor

Sorghum bicolor (L) Moench is receiving significant attention as an energy crop and valuable lignocelullosic feedstock because of its water use efficiency and high biomass yield potential. Due to the advancement of genotyping and sequencing technologies, genome-wide association study (GWAS) has become a routinely used method to investigate the genetic mechanisms underlying natural phenotypic variation. In this study, we performed a GWAS for nine biomass-related plant architecture traits, to determine the overall genetic architecture and the specific role of natural allelic variations in gibberellin (GA) biosynthesis and signaling genes. A total of 102 SNP representative regions were identified associated with all traits and three of them correspond to GA candidate genes affecting plant height, leaf angle and seed number. A previously reported QTL for leaf angle was fine mapped to a 635 kb fragment and ten potential candidate genes in that region were identified. This is the first association analysis between sorghum GA genes and plant architecture traits and, the first GWAS for leaf angle, stem circumference, internode number, tiller number, seed number and panicle length using high-throughput genotyping data. The novel genomic regions controlling phenotypic variation in plant architecture are the most important outcomes of this study and represent the foundation for future validation studies needed to exploit this knowledge in sorghum breeding programs.