Mapping of QTL associated with Fusarium root rot resistance and root architecture traits in black beans

Quantitative Trait Loci (QTL) associated with physiological resistance to Fusarium Root Rot (FRR) and root architecture traits were mapped in a black bean (Phaseolus vulgaris L.) recombinant inbred line (RIL) population. The parents of this population were the landrace Puebla 152 and the cultivar Zorro that differed in root architecture traits. The population was screened against FRR strain FSP-3 in the greenhouse in Uganda and for root architecture traits measured under disease free conditions in the greenhouse in California. The population was also genotyped with 5398 SNP markers using the BARCBean_3_6K Beadchip. Four QTL associated with root architecture traits and one QTL associated with FRR resistance were detected. Total root weight and shallow root weight were associated with the same QTL on chromosome Pv09 at 0.29 Mb. A QTL associated with root length was detected on Pv01 that was independent of the fin gene which controls shoot determinacy. Deep root weight and total plant biomass were associated with the same QTL on Pv05 at 39.20 Mb and mapped 260 kb from the QTL associated with FRR resistance, suggestive of a possible association. None of the QTL accounted for more than 13 % of phenotypic variation, indicative of the fact that several genes of minor influence govern FRR resistance and root traits. Puebla 152 was the source of the beneficial alleles in each QTL detected in this study and is a useful genetic source of root architecture traits that may be valuable in breeding for root rot avoidance in common bean.