A Mutable Gene System in Phaseolus vulgaris L.1
- Dermot P. Coyne2
Variegated plants were observed in the F2 progeny of the Phaseolus vulgaris crosses ‘Yellow Eye PI 209086’ ✕ ‘G.N. Nebraska #1’ and ‘Dark Red Kidney’ ✕ G.N. Nebraska #1. In some environments a phenotypic ratio of 63 normal : 1 variegated plant was observed in the F2, while a 15:1 ratio was found in other enviromnents. The data suggest that the somatic instability which produced the variegated character was due to the action of two genes, one being unstable in the presence of a mutator gene. The third gene apparently had a threshold effect and was only expressed under some conditions. The environment-sensitive gene was designated as “var,” the mutator gene as “mu,” and the unstable gene as “us.” Each of the parents lacked the mutator-unstable gene complex for the development of the character. No variegated plants were found in the F2 of Dark Red Kidney ✕ PI 209806, which indicated that each of these parents possessed either the unstable gene or the mutator gene, but not both. Proposed crosses are discussed by which it is planned to distinguish whether G.N. Nebraska #1 carries the unstable gene or the mutator gene.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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