高温对大白菜小孢子培养的影响

EFFECTS OF HIGH TEMPERATURE ON THE CULTURES OF ISOLATED MICROSPORES IN BRASSICA CAMPESTRIS SSP.PEKINENSIS

应用 FDA和 DAPI荧光显微术观察了高温处理对大白菜 Brassica campestris spp.pekinensis L our. Olsson 小孢子培养的影响 .在 2 5℃恒温培养条件下 ,小孢子的成活率迅速下降 ,至第 7天基本无幸存小孢子 ;小孢子膨胀后呈椭圆形 ,核第一次分裂多为不对称型 ;小孢子丧失胚胎发生能力 .相反 ,在培养开始时 ,先用 33℃高温处理 2 4 h,然后转入 2 5℃培养 ,小孢子成活率虽在第 1天急剧下降 ,但随后仍保持一定水平 ;膨胀的小孢子多呈圆球形 ,小孢子核第一次分裂出现对称型 ,频率可达 4 0 %左右 ;小孢子可进行几种方式的细胞分裂 ,以类似于胚胎细胞的对称分裂方式为主 占总分裂数的 5 5 % ;小孢子经多次分裂可形成紧密的多细胞团 ,最终形成胚状体 .若以高温诱导的小孢子分裂频率为评价指标 ,小孢子接受高温处理的敏感期位于开始培养的 1 2 h内 ,但以胚胎发生频率为指标 ,敏感期位于开始培养的2 4

The influence of high temperature (33℃) on embryogenesis in isolated microspore culture of Chinese cabbage (Brassica campestris spp.pekinensis ) was investigated by microscpopy of FDA and DAPI.The microspores cultured at constant temperature of 25℃ lost their viability quickly and only few viable microspores were found after 7 days of culture.The morphology of the cultured microspores became as turgescent as the “rugby” which was similar to the mature pollen of the Chinese cabbage.The first nuclear division of the microspores was asymmetric.The microspores lost their capacity of embryogenesis under such condition.In contrast, when the microspores were cultured at 33℃ for 24 h before they were transfered to the culture condition of 25℃, their developmental pattern was changed. Some of the microspores could remain viable even for 7 days in culture, they became rounded off.The symmetric nuclear division pattern was induced.The frequency of such division was about 40%. Of the several new cell division types observed, the symmetric type was more frequent (55%) than others.The microspores treated under 33℃ were able to form embryoids via embryogenesis.The critical period of high temperature treatment on microspore culture of Chinese cabbage was about the initial 12 h, if the cell division index of microspore was concerned, but the period was the initial 24 h if the frequency of embryogenesis was considered.