A Search for Candidate Gene for Cowpea Powdery Mildew Resistance in the Southern Guinea Ecology of Nigeria

The need to identify candidate gene for resistance to powdery mildew (PM), a major fungal foliar disease of cowpea in Southern guinea savannah of Nigeria has necessitated this research. An experiment involving 13 cowpea genotypes was laid out in a randomized complete block design (RCBD) of two replications at the Botanical Garden, University of Nigeria, Nsukka, Nigeria. Each genotype was scored for susceptibility to the disease. Four parents were afterward selected for progeny generation through a 2 x 2 factorial mating design. The F1 hybrids were evaluated in RCBD of two replications on the field for powdery mildew resistance. The scored data was transformed by arcsine method before subjection to analysis in SAS (version, 9.3). Analysis of variance (ANOVA) revealed significant (P<0.01) differences among the 13 genotypes in their susceptibility to PM. The male, female and the interaction of both significantly (P<0.001) differed. Additive genetic variance (510.07) was higher than the dominance genetic variance (387.67). Additive gene action was prominent in this study. The broad and narrow sense heritability estimates were: 99.9% and 56.8% respectively. The average degree of dominance was 1.23 and the genetic advance was 62.09. Heterosis which signifies resistance to PM was observed in the crosses between Nsukka-BA x IT89KD-374-57, IT90K-59 x IT89KD-374-57 and IT90K-59 x Nsukka-1B. The identified resistant genotypes (IT90K-59, Nsukka-BA and IT89KD-374-57) would be resources for further breeding programme. Powdery mildew cowpea resistant cultivar development could be achieved through hybridization programme since the major contribution to the inheritance of the trait was additive.

Keywords:

: Powdery mildew, inheritance, genetic advance, gene action F1 hybrids,

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