Studies On The Cytology Characteristic Of The Cytoplasmic Male Sterile Line 8214A In Pepper (Capsicum Annuum L.)

Pepper (Capsicum annuum L.) is a very important vegetable crop. Pepper shows remarkable heterosis. The cytoplasmic male sterile is a very important way to utilize the heterosis in pepper. We have studied the cytological features of developing anther ultrastructure and its nutrition metabolism by using 8214A, and its maintainer line 8214B as material. The results are as follows:1. Comparing the anther ultrastructure of the male sterile and maintainer line. At the stage of microspore mother cell in the anthers of maintainer line, the microspore mother cell nucleolus is big in the center and the cytoplasm is denseness, the anther wall is in differentiation completely. At the microspore mother cell meiosis stage, the mother cells enlarged in volume, it formed chromosome when the nucleus disappeared, the tapetum cells volume enlarged in radial direction and its organelles are abundant. Until to the tetrad stage, the tetrad cells cytoplasm is dense, its organelles are abundant and formed anther wall. The tapetum cells are regular in shape, its organelles are abundant, sporopollenin accumulated in the internal wall of the tapetum cells. At the early microspore stage, the microspore nucleus is big in the center, the tapetum cell is irregular in shape and became degenerated. Then, many small vacuoles formed in the microspore cytoplasm. At the late microspore stage, the small vacuoles fused to a big vacuole, the tapetum is degenerated completely. Then the microspore finished the first mitosis, it formed the bicellular pollen which contain vegetative cell with large central vacuole and germ cell in convex shape. From the late bicellular pollen stage to the mature pollen stage, the starches largely accumulated in the pollen cell and the large vacuole disappeared in the the tapetum cells disappeared in the vegetative cell, the anther wall only left epidermis cells and the endothecium cells which cell wall thicked. In the male sterile line, the ultrastructure were similar to maintainter line at the microspore mother cell stage. After the first meiosis of microspore mother cells, it formed dyad cells, the dyad cell membrane became partly shrink and fracture, the inclusion effusioned, the tapetum cells became degenerated in evidence, its shape is irregular, the density of electrons augmented, the organelles is in largely vacuolation and the nucleolus is not in integrity. After the meiosis, for the locule haven't augmented, the tetrads adhered to each other, the tetrad spore became abnormal, its membrane appeared partly shrink and fracture, there is no sporopollen accumulated in the spore wall. Then, the spore is further shrink, the nucleolus became irregular in shape and come to be many nucleosomes, at last, the tetrad spore became degenerated completely only left the callose shell. At the mature stage, the anther is shrunken and no any pollen.2. A cytoplasm male sterile pepper (Capsicum annum L.) was examined using cytochemical method to study its pollen abortion. Thick sections of both anthers of male sterility line 8214A and its maintainer 8214B at different stages were stained using Periodic Acid-Schiffs (PAS) reaction to detect starch distribution. Anther structure and starch distribution in both anthers of male sterility and maintainer line were similar before the meiosis of microspore mother cells. After meiosis, the size of tapetal cells of fertile anthers of maintainer line increased and became high vacuolation. Abundant small starches appeared in the connective cells from tetrad stage to early stage of microspore development. At the late stage of microspore, the tapetal cells began to degenerate and the starches in the connective cells became large. Bi-cellular pollen synthesized starches after the large vacuole of vegetative cell disappeared, and abundant starches were stored in the mature pollen. In the anthers of male sterile line, meiosis of microspore mother could occurred and the tetrads could be formed in the locule, but the tetrads were extruded together because the locule could not enlarge its space. Finally, the tetrad microspores degenerated. The development of vascular tissue of the sterile anthers was normal and abundant starches were stored in the connective cells, which suggested that the function of plant transporting polysaccharide into anther was normal but tapetum could not transport the polysaccharide into locule. According to our result, the pollen abortion occurred in the tetrad stage and the abnormal development of tapetal cells might be the reason which induced tetrad microspore abortion in this male sterile pepper.