Genetic Variation Analyses On Brassica Napus×Purple-Caitai Hybrids And Their Backcross Progenies

Purple-Caitai (Brassica campestris L. ssp. chinensis L.var. utilis Tsen et Lee. 2n=2x=20) is a variant of Brassica and it is a specialty vegetable of our country. Because of its good taste, crisp refreshing and rich nutrition, it becomes people's favorite vegetable. Existing species of Purple-Caitai only emphasizes earliness, leading to poor quality, so quality breeding is important. Through distant hybridization and backcrossing, the male sterility gene in Brassica (B. napus 2n=4 x=38) can be transferred to Purple-Caitai, then broaden the genetic base of Purple-Caitai. After that, through the use of heterosis, we can improve the quality and increase the yield of Purple-Caitai and provide materials of new varieties. Their hybrid and backcross progeny with wide range of character variation provide a wide range of basic materials for selective breeding.Distant hybridization of a new kind of cytoplasmic male sterility of Brassica napus (2n=4 x=38) and Purple-Caitai was carried out. Purple-Caitai was used as the recurrent parent to continue backcross. Agronomic and quality traits, glucosinolate components of the hybrids and backcross progenies of Brassica napus X Purple-Caitai were analyzed to understand how to change of them with generations. And assessment and selection of meaningful genetic breeding material for quality breeding of Purple-Caitai. The main results were as follow:1. Agronomic and quality traits of the F1 and BC1 to BC4 of Brassica napus X Purple-Caitai were analyzed. The results showed that the donor parent and the recipient parent exhibited nucleus replacement. In F1, agronomic traits of heterosis were significant, but quality traits were not significant. The values of agronomic traits and quality traits of hybridization and backcross progenies had a certain fluctuation and the higher the generation of material, the more similar to the recurrent parent, while the variation range of lower generation was wide.2. Glucosinolate content and components of the F1 and BC1 to BC5 of Brassica napus X Purple-Caitai were analyzed. The total glucosinolate content varied in the hybrids and backcross progenies and the heterosis in Fl is not obvious; total glucosinolate content increased in BC1, but it varied slightly in BC2 to BC5. Glucosinolate components in it were similar to the recurrent parent and became stable with generations; the relative percentage of total aromatic glucosinolate content became similar to the recurrent parent with generations.