INHERITANCE OF BACTERIAL CANKER RESISTANCE IN THE TOMATO LINE HAWAII 7998

Abstract

Clavibacter michiganensis subsp. michiganensis (Smith) Davis et al. incites bacterial canker of tomato and is a significant disease in many tomato growing areas of the world. In previous studies, the accession Hawaii 7998 displayed a high degree of resistance to bacterial canker in North Carolina. Hawaii 7998 and the bacterial-canker-susceptible breeding line NC EBR-3 were crossed to develop reciprocal F1, F2 and BC populations for genetic analysis of bacterial canker resistance. Plants were evaluated for resistance in field and greenhouse studies. The field study indicated no maternal effect. Generation means and variance analysis indicated that foliar resistance was moderate and quantitative. Narrow sense heritability (h2) was estimated as 0.24. By regressing F3 progeny means onto F2 plant values, h2 for foliar resistance was calculated as 0.35. When data for both F2 and F3 generations were transformed into standard units, h2 was 0.44. In greenhouse studies generation means and variance indicated wilt resistance to be quantitative in nature, but h2 was estimated as low (0.09). The F1 generation mean was similar to the resistant parent.