Jinfa Zhang, James McDonald Stewart
Upland cotton (Gossypium hirsutum, AD1) is the most important fiber crop for the world's textile industry. The genetic base of Upland cotton is narrow, and the introgression of germplasm from other species into Upland cotton can broaden its genetic diversity, including the introduction of new qualitative traits. The objectives of this study were to determine the inheritance, allelism, and linkage relationships of the red anther trait introduced into Upland from the red anther donor G. armourianum (D2-1) through crosses involving a synthetic tetraploid A1D2-1. After two generations of backcrossing to Upland cotton, followed by inbreeding, homozygous red-anthered plants (RA) were selected and used for crosses with two Upland lines, the Upland standard TM-1, the multiple recessive marker line T582, and the multiple dominant marker line T586. All Upland cotton parents, except the RA parents and T586 (possessing yellow anthers), had cream anthers. The anther color of the F1 plants was red, indicating that the red anther trait is dominant. In nine of ten F2 populations and four of five testcross populations, the segregation of anther color followed a 3:1 and 1:1 ratio, respectively, as expected under a one-gene model. In three F2 populations with a total of 885 plants between RA with green leaf and T586 with red leaf (R1 on chromosome D07), no double recessive genotype (yellow/cream anther and green leaf) was observed, indicating the allelic relationship between R1 and red anther allele, designated R1a. The recombination frequency between R1a and cluster-1 (cl1) on D07 was estimated to be 0.112 in 256 F2 plants of a cross between RA and T582 based on the maximum likelihood estimation. This new red anther trait and its associated new gene allele provide an important genetic source for understanding the biosynthesis of anthocyanins and may have utility for improving resistance to anther-feeding insects in cotton.