Development of plant breeding technology and new traits of Brassica crops using microspore culture

1.实用育种：利用小孢子培养技术，在大白菜和甘蓝上选育出小孢子胚胎发生能力强、性状与日本品种相似的大白菜新品系。ABA处理的胚胎在4ﾟC下保存1年后，在无菌条件下在盆栽中萌发，有望用于单倍体育种。2.机制：雌雄同体胚胎在早期发育阶段是异养的，但在心形阶段之后是自养的。小孢子胚胎发生的遗传采用4x4双列杂交分析。高胚胎发生能力对低胚胎发生能力是显性的，加性基因效应占主导地位。胚胎发生的遗传力很高。结果表明，有3个标记与小孢子发生有关。3.变异的扩大：考察了紫外光照射对小孢子培养的影响。小孢子对紫外线高度敏感，用软腐液和黑腐液对紫外线照射的小孢子进行体外筛选，筛选出大白菜抗病突变体。以小孢子为靶标，通过直接基因转移和农杆菌介导法获得转基因甘蓝型油菜。4.单倍体育种评价：利用随机扩增多态性DNA技术检测甘蓝型油菜单倍体的遗传固定程度。虽然双亲株系表现出比亲本高得多的一致性，但个体间的差异仍然存在。

1.Practical breeding : The DH lines, which had both high microspore embryogenesis ability and characteristics similar to Japanese cultivars, have been developed using microspore culture in Chinese cabbage and cabbage. The ABA-treated embryos sprouted in pots under unsterile conditions after 1 year storage at 4ﾟC.This storage system was expected to be useful for haploid breeding.2.Mechanism : The androgentic embryos were clarified to be heterotrophic at early developmental stage, but autotrophic after heart-shaped stage. Inheritance of microspore embryogenesis was studied by 4x4 diallel analysis. High embryogenesis ability was dominant to low ability, and additive gene effect was predominant. The heritability for embryogenesis was quite high. RAPD analysis showed that 3 RAPD makers were identified to be associated with embryogenesis.3.Enlargement of variation : The effect of UV irradiation on microspore culture was examined. The microspores were highly sensitive to UV.Using in vitro selection of UV irradiated-microspoes by soft rot-and black rot-filtered solution, disease tolerant-mutants of Chinese cabbage were selected. Transgenic B.napus was produced by direct gene transfer and Agrobacterium-mediated method using microspores as targets.4.Estimation of haploid breeding : The degree of genetic fixation in DH lines was examined by RAPD analysis. Although the DH lines showed much higher uniformity than parental lines, the variation among the individuals still remained.