Genetics of resistance to Fusarium udum in pigeonpea [Cajanus cajan (L.) Millsp.]

Abstract

Fusarium wilt caused by Fusarium udum is an important disease of pigeonpea [Cajanus cajan (L.) Millsp.] in Eastern and Southern Africa. Wilted plants often fail to give any yield if attacked early. Several resistant lines have been reported at International Crop Research Institute for Semi-Arid Tropics (ICRISAT). However, this disease has not been well studied genetically. This study was undertaken to determine the mode of inheritance to Fusarium wilt in lines which are to be utilised as sources of resistance in the pigeonpea improvement program at the University of Nairobi. Two resistant lines, NPP 725 and NPP 726 were crossed with a susceptible line NPP 718. A cross was also made between the resistant lines. The parents, F1 and F2 generations were tested alongside the backcross generations in wilt-sick soil boxes in the glasshouse. Qualitative genetic analyses indicated resistance in both lines to be dominant over susceptibility and controlled by two genes. In the line NPP 725, the gene interaction was inhibitory while in NPP 726, it was complementary. The allelic test between NPP 725 and NPP 726 established independence in these genes. Planned hybridization and backcrossing into local cultivars Is already in progress.