Multi-locus genome-wide association study for grain yield and drought tolerance indices in sorghum accessions

Drought is a significant factor that causes yield loss in essential cereal
crops such as sorghum (Sorghum bicolor (L.) Moench), necessitating the
development of drought-tolerant varieties adaptable to various water
conditions. This study aimed to pinpoint drought-tolerant sorghum lines
and genomic regions for tolerance by utilizing 216 sorghum accessions in
stressed and non-stressed environments at two locations. Genetic diversity
was evident among accessions in terms of grain yield under different
watering regimes. Drought stress indices such as the stress tolerance
index, mean Productivity, geometric mean productivity, harmonic mean
productivity, Yield Stability Index and Yield Index were identified as
effective measures for selecting drought-tolerant sorghum. Cluster
analysis classified genotypes into four groups based on their association
with grain yield, highlighting Acc#28546 and Acc#216739 as highly drought
tolerant across environments. This study identified 32 and 22 Quantitative
trait nucleotides (QTNs) for drought indices and grain yield under stress
and non-stress conditions, respectively, at two locations, with five
common QTNs linked to multiple drought indices. Colocation analysis
revealed that these QTNs were associated with known stay-green-related
QTLs, and 47 putative genes near these QTNs potentially influenced drought
tolerance traits. It is suggested that accession selection considers
multiple indices for robust evaluation. Understanding the identified genes
and their functions provides insights into the genetic mechanisms
governing plant responses to drought stress, offering prospects for
developing improved drought-resistant sorghum varieties through further
genetic research.S.