Multi-locus genome-wide association analysis for root and shoot traits at seedling stage in Ethiopian sorghum (Sorghum bicolor (L.) Moench) accessions

The Ethiopian sorghum germplasm possesses a vast array of genetic diversity across various traits, yet the genetic basis of most characteristics during the seedling stage remains largely unexplored. Understanding the genetic architecture of these traits is vital for developing new sorghum cultivars that can withstand drought conditions. This study aimed to identify genomic regions influencing root and shoot traits during the seedling phase. The research utilized 129 sorghum accessions from different regions in Ethiopia, revealing significant genotype variation (p < 0.001) for all traits analyzed. Through a multi-locus genome-wide association study (ML-GWAS) employing 127,804 high-quality single nucleotide polymorphism (SNP) markers, 49 stable quantitative trait nucleotides were consistently identified by multiple models. Candidate genes associated with various root and shoot traits were pinpointed, such as ALUMINUM-ACTIVATED MALATE TRANSPORTER (ALMT) impacting root length, an F-BOX domain influencing root angle, and FAR1 regulating root hair number for nutrient absorption. Additionally, genes like RING ZINC FINGER, CHLORIDE CHANNEL (CLC), WRKY domain, and DEAD-box RNA helicase were highlighted as potential candidates for traits like shoot dry weight, root dry weight, stomatal density, and stomatal area, respectively, important for plant growth, development, and response to abiotic stresses like drought. These results emphasize the necessity of a thorough understanding of sorghum genetic diversity to guide breeding strategies for improving crop resilience and productivity. This study sheds light on the genetic foundation of seedling root and shoot traits, aiding in the development of sorghum cultivars through marker-assisted selection. Further exploration into the genetic mechanisms underlying these traits and candidate genes could unlock the potential of leveraging seedling characteristics for stress tolerance, contributing to the creation of resilient sorghum cultivars that can thrive in varying climatic conditions.