Multi-locus genome-wide association studies for root system architectural traits in Ethiopian sorghum (Sorghum bicolor L.) landraces.

BACKGROUND

Drought is a major constraint to sorghum production. Developing drought-tolerant sorghum varieties is crucial. Optimal root system architecture (RSA) plays a vital role in plant adaptation and productivity under water- limited environment. Genetic assessments of untapped Ethiopian core sorghum germplasm to identify quantitative trait nucleotides (QTN) for RSA traits are crucial. Therefore, this study aimed to identify genetic markers associated with seven RSA and related traits in 182 Ethiopian core sorghum-landraces using multi locus genome-wide association studies (ML-GWAS) using SNP markers.

RESULTS

The germplasm exhibited substantial phenotypic variation for all measured traits. Genome-wide association analysis identified 181 significant QTNs (LOD ≥ 4) associated with nodal root angle (NRA), shoot traits (length, number, dry weight), and RSA (angle, number, dry weight) across six multi-locus GWAS models. Notably, 73 of these QTNs were consistently detected by at least two ML-GWAS methods. A total of 132 potential candidate genes, ranging from 13 to 25 genes per marker trait for the QTNs, were found about 18kbp LD decay of the significant QTNs using biomaRt. Of these, 13 genes were functionally annotated and involved in various biological processes.

CONCLUSIONS

Following the validation of candidate genes for root architecture and related traits, the core collection can be utilized to develop water-efficient sorghum varieties.