This study investigated the inheritance of resistance to Fusarium oxysporum f.sp. tracheiphilum (Fot) in cowpea lines. Resistant and susceptible cowpea lines were crossed to develop F1, F2 and backcross populations. Reaction to Fot was evaluated in 2015 and 2016 using seed soak and modified root‐dip inoculation methods. The expression of resistance reaction in the F1 and segregation in F2 generations indicated the role of dominant gene controlling Fot in cowpea. These results were further supported by the result of backcross (BC1P1F1 and BC1P2F1) progeny tests. The backcross of F1 with the resistant parent produced progeny that were uniformly resistant, whereas backcross of F1 with the susceptible parent produced progeny that segregated into 1:1 ratio. The F2 segregation ratio in the reciprocal cross showed no evidence of maternal effect in the inheritance of the resistance. Allelism test suggests that the gene for resistance in TVu 134 was the same in TVu 410 and TVu 109‐1. We also identified an SSR marker, C13‐16, that cosegregated with the gene conferring resistance to Fot in cowpea.

Cercospora leaf spot (CLS) caused by Pseudocercospora cruenta (Sacc.) is an important disease affecting cowpea production in Nigeria. Understanding the genetic nature of CLS is an important step in developing an effective breeding strategy. This study investigated the inheritance of CLS disease in cowpea under natural epiphytotic field condition involving two CLS resistant parents (IT99K-573-1-1, IT99K216-24) and a CLS susceptible parent (UAM09-1055-6). The parental lines, F 1 , BC 1 P 1 , BC 1 P 2 , F 2 and F 3 generations were used to study the genetic nature and to detect SSR markers closely linked with the CLS resistance gene(s) using bulked segregant analysis (BSA). The result showed that F 1 populations involving UAM09-1055-6 9 IT99K-573-1-1 and UAM09-1055-6 9 IT99K-216-24 were resistant to CLS in the 2 crosses suggesting the presence of gene dominance in the control of the disease. The observed segregating ratio of F 2 populations fits the Mendalian ratio 3:1. The plants reaction to the disease in the backcross progeny test involving the resistant parent were all uniformly resistant, whereas those involving the susceptible parent segregated into ratio 1:1. The F 3 generations, which segregated into ratio 1:2:1 further confirmed that resistance was controlled by a single dominant gene in the crosses studied. Heritability estimates varied from 81 to 97%. BSA showed that SSR marker code named RB24 of lima bean and validated on F 2 population discriminated between resistance and susceptibility to CLS. Hence RB24 could be a useful marker for marker-assisted selection in CLS resistance breeding in cowpea.