Association mapping for Striga resistance and agronomic-related traits in sorghum

Over 50% of arable land available for cereal production in sub-Saharan Africa is severely infested with Striga hermonthica (Del.) Benth, posing a significant challenge to agricultural productivity in the region. In this study, we performed association mapping of plant height, panicle height, number of leaves per plant, field fresh grain weight, dry grain weight, and chlorophyll with 6,094,317 single nucleotide polymorphism (SNP) markers for Striga resistance genes in diverse sorghum [Sorghum bicolor (L.) Moench] breeding lines and varieties released for resistance breeding. Chromosomes containing significant SNPs in FASTmrMLM and FarmCPU models were identified and computed. Chromosomes 1, 2, 3, 4, and 6 harbored SNPs significant for Striga tolerance in sorghum for agronomic-related traits. Agronomic traits measured revealed significant SNP counts as follows: plant height (4), panicle height (3), leaves per plant (2), foliar fresh grain weight (8), dry grain weight (2), and chlorophyll content (3). After successful validation, the 22 newly identified SNP markers linked to Striga resistance can be used for trait introgression and marker-assisted selection to increase Striga resistance in sorghum. We detected 12 SNPs using the FASTmrMLM model without adjusting the threshold level. However, no significant SNPs were detected with FarmCPU before the threshold was adjusted. Also, we identified 95 significant SNPs upon lowering the Bonferroni threshold value to p < 0.001. The parent materials for the intraspecific cross that produced the currently accessible molecular map were selected from the gene pool of cultivated sorghum. This map is invaluable for real-world breeding applications. Subsequent crosses among cultivated sorghum genotypes of interest to breeders will likely produce polymorphic segregating Diversity Array Technology (DArTSeq) markers within the cultivated gene pool.