Inheritance of the Two-points Pattern of Partly Colored Seedcoats in Common Bean

Abstract

Common bean (Phaseolus vulgaris L.) seedcoats can have partly colored patterns such as the new two-points pattern, which has an unknown genotype. The gene tcf (derived from PI 507984) expresses partly colored seedcoat pattern with colored flowers. A genetic tester stock tcf two-points BC3 5-593 was derived from PI 507984 by backcrossing to the recurrent parent, Florida dry bean breeding line 5-593, which has black self-colored seeds and purple flowers due to the genotype T P V. A series of test crosses were made between tcf two-points BC3 5-593 and three genetic tester stocks: t z jers white BC3 5-593, t z bip bipunctata BC3 5-593, and t z virgarcus BC3 5-593. All three test crosses were studied in F1 and F2 populations, and the latter test cross in F3 progenies derived from 80 randomly selected F2 plants. The two-points pattern was never observed with white flower plants expressed by t/t, supporting the hypothesis that tcf is necessary for two-points expression. The complete genotype for two-points was found to be tcf z jers. The tcf gene expresses more extensive colored zones in partly colored seedcoats than t. For example, tcf z J expresses self-colored seedcoats, whereas tcf/t z J expresses white ends pattern and t z J expresses virgarcus. Similarly, the tcf z jers genotype expresses two-points pattern, whereas t z jers expresses white seedcoat; and tcf/-z J/jers expresses PI type pattern, whereas t z J/jers expresses weak virgarcus pattern.