BREEDING A GENIC AND CYTOPLASMIC DOUBLE-MS LINE OF RAPESEED (BRASSICA-NAPUS L)

All rapeseed lines with Polima male sterility (MS) that are applied in hybrid cultivars have the problem that their sterility varies with te mperature. To overcome this problem, two double-MS lines with genic (G MS) as well as cytoplasmic male sterility (CMS) genes were synthesized through seven generations of breeding, based on a systematic study of changes in fertility of the genic and cytoplasmic male sterility line s. The fertility of the new sterility lines was determined by observat ion of the floral organs and by pollen staining. The results showed th at, in the double-MS lines, half the plants maintained the features of the Polima CMS line, while the other half behaved like the GMS line. The GMS genes were correctly expressed in the Pol cytoplasm, but there was little interaction between the GMS and CMS genetic systems.