The Heredity And Cytological Study On Male Sterility In Amphidiploid Between Raphanus Sativus And Brassica Alboglabra

Distant hybridization is an important strategy for plant breeding, germplasm enhancement and novel male sterile lines creating. Brassica include abundant and extensively used genetic accessions. Great efforts of intarspecies cross in Brassica and interspecies cross between Brassica and Raphanus, Sinapie, Diplotaxis have been made, creating many new varieties or male lines of rapeseed and vegetables.In this study, the morphological features of amphidiploid between Raphanus sativus and Brassica alboglabra was observed. In addition, the heredity and cytological characteristics of male sterility line 8109 derived from this amphidiploids were studied. The main results are as follows:1) The amphidiploid was morphologically different from its parents. There were cleft leaves at base, and the parietal leaves were large and round with a small amount of wax powder, of which surface was smooth; The floral organ developed normally, similar to paternal Brassica alboglabra, but with white and larger petals compared to patents; The pod showed dumbbell-like, the external morphological characteristics of which in top half was similar to Raphanus stativus pod with serious lignification and cracking difficultly. On the contrary, the skin of lower part of pod was thinner and easy to crack, that was similar to Brassica alboglabra.2) The male sterility line 8109 showed some abnormal phenotypes, such as dead buds, short stamens, white and triangular anther and non-pollen.3) Through the pollen viability test, self-pollination test, and other methods, we found the male sterility line 8109 is sterile completely. The male sterility line 8109 had been crossed with other varieties, and two restorer lines 8024 and 8057 were found.4) The F2 population segregated at a 3:1 ratio for fertility/sterility, and the BC1 population segregated at a 1:1 ratio for fertility/sterility, following the segregation proportion of a single recessive gene. These results suggested that the fertility was controlled by a single recessive gene.5) To observe the developmental differences between male fertile and male sterile anthers, microscopic observation on anther development process of fertile and male sterile anthers was performed with paraffin sections. The results showed that the key stage of male sterility was from tetrad to microspores. At this stage, many layers cell appear on tapetum. With the development of microspore, the tapetum of male sterile anther enlarged radial with a number of larger vacuoles; the surface of male sterile microspore was smooth without exine formation. Till the stage of later microspore, tapetum and microspores were disaggregated to be an empty pollen sac.