Genetic analysis for bacterial wilt resistance in a tomato cross, Lycopersicon esculentum Mill x L. pimpinellifolium Mill.

Genetic analysis for bacterial wilt resistance in a tomato cross, Lycopersicon esculentum Mill x L. pimpinellifolium Mill.

1972

p.183-190

SB183.2.C75 1972

The inheritance for resistance to bacterial wilt (Pseudomonas solanacearum E. F. S.) in tomato was studied by taking weekly death counts of about 13,000 plantss grown under conditions of severe bacterial wilt. The progenies scored were derived from crosses of a susceptible commerical variety and a wilt resistant inbred from the speices, Lycopersicon pimpinellifolium Mill. Results obtained from field trials in four seasons were corroborated by tests in wilt-inoculated flats and tile beds. The severity of the disease varied seasonally, with the most severe expression in the summer months, at times of highest soil temperatures. Survival curves for the susceptible parent and F1 were exponential with time, 50 percent lethality occurring at about 4.5 and 16 weeks, respectively, after transplanting to the field. The resistant parent rarely succumed to wilt in the field, and most plants survived the end of a good fruit-bearing period. Bakcrosses of F1 and the susceptible parent segregated widely in time of death, with exponential killing starting in about the 12th week. The other backcross was similarly intermediate to its parents, and F2 and F3 segregants were classified as equally susceptible as the susceptible parent. The data from segregating families were interpreted multi-factorially, in the absence of convincing evidence of one or a few major genes for resistance. Partial dominance of genes conferring resistance could be suggested from the data, but with the caution that another choice of scale of measurement might change this conclusion. Otherwise, gene action must be held to be entirely additive. [AS]

Crop Science Society of the Philippines, third Annual Scientific Meeting 1972; Proceedings of

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