Genome-wide association analysis uncovers genes associated with resistance to head smut pathotype 5 in senegalese sorghum accessions

Authors: Ahn, Ezekiel; Prom, Louis; Park, Sunchung - Sun; HU, ZHENBIN - Non ARS Employee; MAGIL, CLINT - West Texas A & M University

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2024
Publication Date: 3/29/2024
Citation: Ahn, E.J., Prom, L.K., Park, S., Hu, Z., Magil, C. 2024. Genome-wide association analysis uncovers genes associated with resistance to head smut pathotype 5 in senegalese sorghum accessions. Plants. 13(7):977. https://doi.org/10.3390/plants13070977.
DOI: https://doi.org/10.3390/plants13070977

Interpretive Summary: A newly identified pathotype 5 of the soil-borne fungus Sporisorium reilianum, which causes head smut in sorghum [Sorghum bicolor (L.) Moench], was tested against 153 Senegalese sorghum accessions. Some sorghum lines exhibited complete resistance to the fungus, while others displayed varying degrees of disease incidence. The responses of sorghum against S. reilianum were explored to analyze the potential linkage between previously known seed morphology traits and newly measured seed weight. In addition, disease response data was correlated with genomic information, and rigorous statistical analysis was performed to pinpoint potential genes associated with the disease incidence rate. The findings provide valuable insights into how sorghum defends itself against the newly emerged pathotype 5 of S. reilianum. Understanding the molecular genetic mechanisms behind the disease resistance can help breeders develop more resilient sorghum varieties.

Technical Abstract: In 2011, two new pathotypes (P5 and P6) of Sporisorium reilianum were identified among head smut isolates collected from South Texas, an area with high-density grain sorghum production. A mixture of pathotype 5 (P5) strains of S. reilianum was tested against 153 previously unexplored Senegalese sorghum accessions. While 63 lines displayed complete resistance, the remaining 32% exhibited disease incidence ranging from 1% to 25%. Sorghum responses against S. reilianum were explored to analyze the potential correlations between previously known seed morphology traits and newly phenotyped 59 lines for seed weight. Employing a genome-wide association study (GWAS) with 297,876 single nucleotide polymorphisms (SNPs), we identified significant associations and promising candidate SNPs with high statistical significance. When mapped onto the sorghum reference genome, the top genes associated with these SNPs revealed roles in plant disease defense. This discovery provides valuable insights into the genetic mechanisms underlying resistance to the newly emerged pathotype 5.