Inheritance of R Locus Expressing Brown Hilum on Black Seed Coat in Soybean

Color is one of the phenotypic markers mostly used to study soybean (Glycine max L. Merr.) in the study of genetic, molecular and biochemical processes, due to their easy recognizability. The genetic control of several soybean natural variants has not been studied. The standard phenotype of R gene is black hilum on black seed. The genetic type T16 is the only occurrence with brown hilum on black seed coat and its genetic control was not described until now. The aim of this study is to understand the genetic control of seed coat and hilum color in the genetic types T16 and in the natural variants of Bragg, BR6 and BR13. T16 was combinined with Bragg P and BR13P (black seed color) and BR6M (brown seed color) and T236 (r-m). It was found that the genetic control of the brown hilum trait in black seed coat of the T16 genotype was controlled by two loci segregating independently and controlling the expression of the color of the hilum and the seed coat color. The expression of the brown hilum trait in black seed coat is dependent on locus T_, which controls pubescence color; therefore it occurs only in genotypes with tawny brown pubescence (T_), which caracterizes the pleiotropic effect of this locus on the trait hilum brown trait in black seed coat. The color of the hilum and the seed coat color belong to the same allelic sequence. No maternal effect was found in the expression of hilum brown trait in black seed coat.