THE MARGO (MAR) SEED COAT CHARACTER AND THE T-MAR INTERACTION IN COMMON BEAN

The inheritance of the seed coat color and color patterns of PI 527753 and PI 527811 was investigated. Dark color expression is usually restricted to the hilum ring and caruncula stnpe zones, and the remainder of the seed is offwhite Analysis of testcross and F2 data demonstrated that PI 527753 carries alleles t mar V and PI 527811 carries alleles t mar v, where t controls partly colored patterns and mar controls margo pattern and color effects. The t mar combination drastically restricts the area of the seed coat with color expression and is epistatic to the usual color-extending effects of the genes for partly colored seed pattern Arc, Bip, exp, and diff. The hypothesis is proposed that mar achieves its effect on seed coat coior and pattern by retarding the development of seed coat color with respect to the other plant tissues; thus, the mature seed have immature seed coat colors, especially in the regions beyond the margo zone. © 1994 The American Genetic Association.