Genome-wide association study reveals genomic loci influencing agronomic traits in Ethiopian sorghum (Sorghum bicolor (L.) Moench) landraces

Uncovering the genetic basis of agronomic traits in sorghum landraces that have adapted to various agro-climatic conditions would contribute to sorghum improvement efforts around the world. To identify quantitative trait nucleotides (QTNs) associated with nine agronomic traits in a panel of 304 sorghum accessions collected from diverse environments across Ethiopia (considered to be the center of origin and diversity), multi-locus genome-wide association studies (ML-GWAS) were performed using 79,754 high quality single nucleotide polymorphism (SNP) markers. Association analyses using six ML-GWAS models identified a set of 338 significantly ( LOD ≥ 3)-associated QTNs for nine agronomic traits of sorghum accessions evaluated in two environments (E1 and E2) and their combined dataset (Em). Of these, 121 reliable QTNs, including 13 for flowering time ( DF ), 13 for plant height ( PH ), 9 for tiller number ( TN ), 15 for panicle weight ( PWT ), 30 for grain yield per panicle ( GYP ), 12 for structural panicle mass ( SPM ), 13 for hundred seed weight ( HSW ), 6 for grain number per panicle ( GNP ), and 10 for panicle exertion ( PE ) were consistently detected by at least three ML-GWAS methods and/or in two different environments. Notably, Ethylene responsive transcription factor gene AP2/ERF, known for regulation of plant growth, and the sorghum Terminal flower1/TF1 gene, which functions in the control of floral architecture, were identified as strong candidate genes associated with PH and HSW , respectively. This study provides an entry point for further validation studies to elucidate complex mechanisms controlling important agronomic traits in sorghum.