IDENTIFICATION AND GENETIC-STUDIES OF THE INHIBITION OF DOMINANT MALE-STERILITY IN BRASSICA-NAPUS

By transferring dominant male sterility (DMS), caused by the gene his, to genotypes with various types of cytoplasm 12 DMS lines were develo ped and a number of crosses made between the DMS lines and other genot ypes of Brassica napus. During the course of this population improveme nt programme, 16 genotypes were identified as having the capacity to r estore the fertility of F-1 plants with the Ms gene. According to pedi gree analysis, the inhibitory gene in those lines probably originated from a few genotypes from Australia and Germany. In further studies th e inheritance of the sterility inhibition was determined, providing de finite evidence that dominant male sterility and its inhibition in B. napus are controlled by two dominant interacting genes rather than by multiple alleles.