GENETIC ANALYSIS OF MUTANTS FROM IRRADIATED COWPEA (Vigna unguiculata [L.] Walp.) SEEDS AND POLLEN

Cowpea, Vigna unguiculata, is an important human and livestock protein source in Nigeria, but its production is constrained by ravages of pests and climate change. Conventional breeding efforts used to fortify it against these constraints had resulted into its narrow genetic base. In order to overcome this challenge, other mutation procedure such as physical and chemical mutagens could be used. Nevertheless, information on gamma and ultra-violet (UV) irradiated cowpea seeds and pollen has not been adequately documented. Therefore, genetic analysis of cowpea mutants from gamma and UV irradiated seeds and pollen, respectively was investigated. Cowpea accessions seeds: IB, IB-Y1, IB-CR and IB-BPC from the University of Ibadan and IT86D-719, IT86D-1010, IT89KD-347-57 and IT90K-284-2 from International Institute of Tropical Agriculture were irradiated at 100, 200, 300, 400 and 500 Gy doses at the rate of 202 Gy/min using 60 Co gamma. Pollen were irradiated for 60, 120, 180, 240, 300 and 360 minutes at 30,000µWs/cm 2 UV prior to hand self-pollination using standard procedures. Radio-sensitivity of irradiated accessions were determined using seed germination (SG), seedling survival (SV), lethal dosage 50% (LD50) for SG and SV, primary leaf area (PLA) and seed set (SS) at M1 and M2 generations. The M1 of gamma irradiation (GI) and M2 of UV irradiation (UVI) treatments were advanced to M2GI and M3UV for phenotyping on field and their genetic stability confirmed at M3GI and M4UV, respectively. Genetic diversity of all mutants was determined using microsatellites. Ribulose-bisphosphate carboxylase primers were used for sequence analysis and classification of the mutants. Inheritance pattern was evaluated at M5 of gamma induced mutants (GIM) for erect-tall (ER), yellow flush (YF), four-primary leaf (FP), crinkled leaf, lettuce leaf (LL), twisted-pale leaf (TP) and burnt leaf (BL) traits. Data were analysed using descriptive statistics and Chi-square at α0.05.