Realised genetic gain and predictive ability across breeding cycles for cooking time in common bean based on multivariate genomic selection

Common beans ( Phaseolus vulgaris L.) are a major source of protein and energy in sub-Saharan Africa, but their long cooking time (CKT) imposes social, economic, environmental and health burdens. This study aimed to accelerate genetic gain for shorter CKT while maintaining or improving other seed traits such as seed iron (Fe) and zinc (Zn) content, water absorption capacity (WAC) and 100-seed weight (SW100) across rapid cycles of early-generation genomic selection. Two related founder populations were selected from the African bean panel and intercrossed in 2020 (population A) and 2021 (population B), followed by rapid two-year cycles of augmented S ₀ -derived family selection. Best linear unbiased predictions (BLUPs) of breeding values were obtained from pedigree, genomic and single-step (combined pedigree and genomic) multivariate linear mixed model analysis across two cycles. Shorter CKT was correlated with higher WAC but lower Fe and Zn. Realised genetic gain from cycle 1 to cycle 2 was high for CKT (average -8.0 min y ^-1 ) and WAC (average +7.7% y ^-1 ), but was accompanied by small decreases in Fe, Zn and SW100. Genomic and single-step models resulted in high accuracy of BLUPs and moderate predictive ability across breeding cycles. The predicted genomic BLUPs for CKT in cycle 2B S ₀ seedlings were strongly correlated by rank with their realised genomic BLUPs in S ₀ -derived self bulks one year later, especially in a leave-one-trait-out approach in single-step multivariate genomic analysis. Indirect selection in S ₀ progeny plants based on correlated and easy-to-measure traits may increase the rate of genetic gain in all traits.