Creation Of Rapeseed Aneuploids By Chromosome Doubling Technique

Chromosome-doubled (CD) seedlings (2n=4x=76) were obtained from homozygous rapeseed (Brassica napus L.) line NJ230 by colchicine treatment. The CD plants have been successively self-crossed for three generations and chromosome number and traits in the self-crossed progenies were observed. The results are shown as follows:1) A doubling percentage of 53.57% was obtained when germinated rapeseeds were treated with 10mg/L colchicine. Plantlets were regenerated on the solid MS medium without any growth substance. Roots were formed on 1/2MS + 0.1mg/L IBA + 0.1mg/L NAA.2) The CD plants (D1 generation) were dwarfed, measured only 70-80cm height; without main branch after bolting and showed good growth vigour. The leaves of the CD plants were bigger and thicker, while the leaf type was similar to rapeseed. The blossom of CD plants was about ten days earlier than parents. Even pollen viability was low, seeds could be produced by self-inbreding. The seed colour was black and same with parent.3) Variations in self-crossed generation of D1 (D2 generation) were rich in agronomic traits and fertility property, etc. And many mutant plants such as male sterile, large silique, large spike, and leaf color etiolating properties were discovered. It was also found that separation occurred with the character of seed colour, which presented hereditary consistency feature between upper and subsequent generation: some plants have black-seed, some have yellow-seed and others have mixed seed of yellow-seed and black-seed.4) The chromosome number of the self-crossed generation D3 and D4 plants tended to be 2n≤38, and most of plant chromosome numbers were 2n=30,32,34,36,38. It shows that the chromosome in self-crossed progenies lost and subducted becausing of adaptability and abnormal hereditary.5) By chromosome number counting, a yellow-seeded aneuploid line with chromosome number 2n=32, was sorted out from self-crossed progenies. The line has a high averaged fertility up to 92.0±4.3%, which is the same as the one of its parent. In agronomic traits, it was better among the ten lines investigated, having significant difference compared with parent. Especially in seed coat colour it was pure yellow, while the parents were black. This yellow-seeded aneuploid line provides material to study the genes about seed coat colour.