Analysis On Cytological、Physiological And Biochemical Of Cytoplasmic Male-Sterility In Cabbage(Brassica Oleracea L)

Head cabbage(Brassica oleracea L. var. capitata L.),2n=2x=18, or short cabbage, derives its origin from the Mediterranean Coast, evolves from annual non-heading wild cabbage through long-term cultivation and has the trait such as wide adaptability, easy cultivation and resistance to storage that cabbage has been cultivated all over the world. As an important vegetable, head cabbage has been widely planted since introduced into our country from the16th century and now cultivated area of head cabbage has reached to more than10,000,000acres. Because of obvious heterosis, the most promising is utilizing of sterile lines. It has the advantage such as saving large amount of manpower and materials, reducing the cost of hybrid seed, improving the quality of the seed and obtaining high purity of hybrid generation. In this study, we used cytoplasmic male sterility line PM and its maintainer line PF as materials to analyze the difference between the two line from morphology, cytology, physiological and biochemical characteristics as a result of exploring abortive mechanism of cytoplasmic male sterility. The cytoplasmic male sterile materials PM has100percent rate for both the sterile plant and sterile degree.This research had a comparative study mainly around the cytoplasmic male sterile material PM and its maintainer line PF as follow:investigating the form of flowers organs and field traits; observing the ultrastructure of nectary of sterile line PM and PF by using scanning electron microscope; utilizing of optical microscope and electron microscope technology to observe microscopy and ultra microstructure of anther and microspore in PM and PF; measuring the physiological and biochemical indexes associated with sterility.The main results are following:1. The investigation about flowers organs form and the field traits indicated that:the buds of PM appeared bright yellow and part of full. The anther was shrivelled, thinness and without splits, couldn’t shed pollen after flowering and slightly higher than stigma or flush with them. On the contrary, the PF buds were full, fruity, slightly green. With the growth of the bud, the size of anther was enlarged and the color changed from light yellow to yellow and became golden yellow at last.The anther was above stigma and the pollen went out as matured.2. The ultrastructural observation of pollen grain and nectary in PM showed that:the nectary development of sterile line was normal and had the same structure with maintainer line. The nectary was composed of a pair of lateral nectary which located inside of short stamens and appeared kidney shape, bumpy surface, full and fruity and a pair of medial nectary which outside the short stamens, showed papillary and stretched angle outward.3. Cytological observation of cytoplasmic male-sterile anther and microspore of PM declared that: abortive period occurred form tetrad period to single nucleus pollen period. The tapetum cells were showed to possess high vacuolization and thicken to squeeze microspore. As a result, the deforming microspore could not divide to binuclear pollen and formed abnormal pollen sac. Further observation for microspore and tapetal cell by using transmission electron microscopy (SEM) technology indicated that pollen mother cells began to appear abnormal and manifested as irregular shape and disorderly arrangement while still divided to dyad and further divided into tetrad. The highly vacuolization tapetum cell microspores degenerated prematurely during development that there could not release the tetrad and plasmolysis occurred in microspore. The process of pollen abortion at cytological and sub-cytological level had the same performance. The development of PF anther expressed normal and finally formed the complete structure of anther and pollen grain through the normal process of cell division.4. The analysis on physiological and biochemical index made a result that:the contents of soluble sugar and soluble proteins and the activity of SOD and CAT in PM were lower than that in PF. The total contents of malondialdehyde in sterile lines were always higher than its in maintainer lines. The activity of POD in PM was below PF in early period but increased with development of buds and PF was just the opposite. The free proline content in PM was far lower than PF.