Genome-wide association studies of antimicrobial activity in global sorghum

Sorghum [Sorghum bicolor (L.) Moench] is a common feed grain globally with vast genetic and phytochemical diversity that may provide numerous health benefits, including its aptitude as an antimicrobial feed grain. This study highlights the antimicrobial potential of a collection of 384 diverse sorghum accessions against two prominent foodborne pathogens, Clostridium perfringens and Salmonella enterica. Following extensive screening, we determined that sorghum grain extract is more efficient at inhibiting C. perfringens than S. enterica. Antimicrobial activity observed against C. perfringens was not significantly correlated with either total phenols (r = 0.12) or tannin concentration (r = 0.12). Moreover, we mapped loci associated with antimicrobial activity to C. perfringens that are independent of loci associated with total phenols and tannins. The two most significant associations were determined to have an epistatic interaction and 20 candidate genes were identified. By sequence homology studies, we found the potential functions of these candidates to include plant stress response (Sobic.002G083600) and phenol metabolism regulation (Sobic.010G222600). Additionally, we noted no relationship between antimicrobial activity and either grain yield or composition. These results highlight significant heritable variation of antimicrobial activity in sorghum that may be useful for breeding to improve its value as a feed source by incorporating grain-based antibiotics in animal production.