Studies On The Mechanism In Cytology And Physiology Of The Cytoplasmic Male-sterility In Pepper (Capsicum Annuum L.)

Pepper (Capsicum annuum L.) is one of the most important vegetable crops for its rich nutrient and economic values. Pepper shows remarkable heterosis. Producing hybrid seeds using the cytoplasmic male sterile line as female parent is a very important way to utilize the heterosis in pepper. However, basic research on the mechanism of cytoplasmic male-sterility in pepper is very limited compared to that in other crops like maize, cotton and rice. The cytoplasmic male sterile lines 9704A and 8214A are bred and selected from a natural pepper mutant of cytoplasmic male-sterility by the National Hot Pepper New Variety Technology Research and Development Center. Research on the cytology , physiology and biochemistry in two male sterile lines is nearly blank. To reveal the mechanism of male sterility occurring in 9704A and 8214A and speed up its application progress, the morphology, cytology, photosynthesis, respiration, membrane lipid peroxidation, endogenous polyamines and phytohormones levels were studied systematically by using 9704A, 8214A and their maintainer lines 9704B and 8214B as materials. The results are as follows:1. The mature anthers of 9704A and 8214A are shortened and diminished compared to those of 9704B and 8214B. The vertical and horizontal diameter of the anthers in the CMS lines is less than those in the maintainer lines when the calyx lobe of the buds is slightly splayed. There is no differences in the dynamics of the buds and the style development between the CMS lines and the maintainer lines. The development of vascular tissue in the connective of the CMS lines is normal.2. The abortion type of these CMS lines is sporophyte abortion. The nucleus of the tapetum cell of the CMS line lyses and the taptum disintegrates prematurely, the disintegrated taptum infiltrate into the location around the pollen mother cell and conglutiolates with the pollen mother cell, the pollen mother cell can't develop into tetrad because its meiotic division can't go on. The taptum of the maintainer line is glandular. The middle layer cell won't degenerate when the tapetum disintegrates prematurely, This proves the hypothesis that the middle layer cells offer nutrients for the tapetum.3. The Chlorophyll content and the net photosynthetic rate in the leaves of CMS linesis normal, and there is no difference between the CMS lines and the maintainer lines.4.There is no difference in the respiration rate in the buds in the early stage between the CMS lines and the maintainer lines, but in the intermediate stage and the later stage, the respiration rate in the buds of the CMS lines is lower than that of the maintainer lines. The rate of alternative respiration and the ratio of alternative respiration and total respiration in the leaves and buds of CMS lines is lower than those of the maintainer lines. Showing a close relation between the fertility of the anther and the rate of alternative respiration.5. The rate of production , content of MDA and the activity of POD and SOD in the buds of CMS lines is higher than those of the maintainer lines, but the activity of CAT in the buds of CMS lines is lower than that of the maintainer lines. The rate of production and the activity of POD and SOD in leaves of the CMS lines is also higher than those of the maintainer lines, but there is no difference in the content of MDA and the activity of CAT in the leaves between the CMS lines and the maintainer lines. This showsthat the sterility in the male sterile lines is caused by the rise of the level and the membrane lipid peroxidation but not the activity of the protective enzymes.6.The ERR (ethylene release rate) in the buds of the CMS lines is higher than that in the maintainer lines. The ERR in the leaves is lower than in the buds, and there is no differences between the CMS lines and the maintainer lines.7. In the leaves and buds of the pepper, putrescine is the major polyamine. The content of putrescine in the buds of CMS lines is higher than in those of the maintainer lines, but this difference does not exist...