A Rapid Growth Of The Synthesis Of New Brassica Napus Microspore Culture

Brassica napus L. is the most widely planted oilseed crop in the world. It possesses of many advantages, such as wide adaptability, high yield, good resistance to diseases and different stresses etc. But the inheritance background of B. napus is relatively narrow compared with the other species of Brassica. The simplex genetic basis is very obvious. Now many scholars analyze and investigate the rape genome based on the research results of mode plant Arabidopsis thaliana. But it is difficult to improve the rape germplasm by utilizing the A. thaliana data. Because B. napus possesses a complex polyploid genome with numerous copies of most genes, and many important agronomic and seed quality traits do not show usable phenotypes in the model species. On the other hand functional genomics and reverse genetics approaches are difficult in large crop species due to the long life-cycle and the large space requirements for testing of experimental populations under controlled conditions. So-called"rapid-growing"Brassica mutants, which have a considerably shortened life-cycle and smaller growth habit than the crop varieties, provide an interesting alternative for experimental studies within the Brassica crop species.In our research a rapid-growing B. napus (AACC) was obtained by protoplast fusion between B. rapa L. (AA) and B. oleracea L. (CC) both of which were rapid growing species. The period from planting to maturity of the resynthesized material needs merely 8 weeks. The size of the material is small amd propitious to reproduce in large amount. The synthesized B. napus is self-incompatible, which prevents the development of highly homogeneous inbred lines for experimental purposes.In this thesis somatic hybrids between B. rapa and B. oleracea were regenerated by PEG-mediated fusion. Cytologicla and morphological observation were done. The microspore culture of the hybrids was carried out to produce DH lines. The results were described as follows.(1) Somatic hybridization of B. rapa and B. oleracea was carried out and the technical system of plant regeneration was established. There are many factors affecting the regeneration frequency of the fused protoplasts, among which culture conditions had a significant impact on cell division and shoot regeneration frequency. The culture conditions covered the combinations of enzyme for protoplasts isolation, combinations of medium, the proportion and sorts of hormone, the density of the protoplasts and so on.(2) Somatic hybrids between the two species were obtained. The morphological and cytological observation of the regenerated plants was carried out. The chromosome number of hybrids is the sum of both parents, i.e. 2n=38. The height of plant was 70-80 cm, exhibiting higher fertility with more than 95 % pollen fertility, and the whole life cycle lasts 8 weeks.(3) Microspore culture-derived plants were produced and the DHs were gained by treating with colchicines. We use microspore culture to generate homozygous inbreed lines or completely homozygous doubled-haploid (DH) lines as a model system for experimental functional genomics work in B. napus.