Progress in the utilization of Cajanus platycarpus (Benth.) Maesen in pigeonpea improvement

Cultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow genetic base; hence, utilization of wild relatives in the crossing programme would broaden its genetic base and introduce useful traits. Cajanus platycarpus (Benth.) Maesen, an annual wild relative from the tertiary gene pool, was successfully crossed with the cultigen, utilizing hormone-aided pollinations, embryo rescue and tissue culture techniques, and backcrossed using cultigen as the recurrent parent. Advance generation progeny showed a range of useful traits such as resistance to phytophthora blight, pod borer, bruchid and podfly resistance. Variation was also observed for plant type, growth habit and seed colour. Anew source of cytoplasmic male sterility was identified in one of the progeny lines. Molecular analysis of the progeny after four backcrosses showed the presence of genomic segments from C. platycarpus accompanied by the presence of recombinant DNA sequences signifying recombination between the parental genomes.