Response of pigeon pea genotypes to different races of Fusarium udum and the mode of gene action responsible for disease inheritance

Abstract

To develop high yielding Fusarium wilt resistant varieties, it is essential to identify new sources of resistance that can withstand multiple races of the pathogen. The aim of this study was to identify [Fusarium udum (L.) Millsp.] races occurring in the study fields, determine reaction of pigeon pea hybrids to the different isolates and establish the mode of gene action responsible for Fusarium wilt inheritance. Field and pot experiments were conducted during 2009 and 2010. A root-dip inoculation and transplantation technique in pots and sowing in a wilt-sick field were used for studying the reactions of 54 pigeon pea genotypes to F. udum isolates. Field evaluation was done in the infested plot in a 9 x 6 alpha lattice design with two replications. Purification of the isolates on potato dextrose agar identified three isolates and were designated as ISO-A, ISO-B, and ISO-C. The isolates produced whitish to light pink or orange mycelia. Purple was predominant on the substrate, but whitish to light pink were also identified. Pot inoculation trials with the three isolates identified seven genotypes (ICPB2043, ICP12012, ICP13092, ICPA2039xICP13092, ICPA2043xICP12012, ICPA2043xICP13092, and ICPA2043xICP9135) resistant to all the isolates. Under field evaluation, seven genotypes (ICPA2039xICP13092, ICPA2039xAsha, ICPA2043xICP12012, ICPA2043xICP13092, ICPA2043xICEAP557, ICPB2043, and Maruti) were moderately resistant. The cytoplasmic male sterile (A) line, A2043, showed resistance to the three isolates. The resistant hybrid, ICPA2943xICP12012 had the highest negative SCA that was highly significant for all the isolates in the field.

Keywords: Fusarium udum, pigeon pea genotypes, pigeon pea isolates, Kenya, wilt-sick field

J. Trop. Microbiol. Biotechnol. 8:9-19 9