STARCH GRAINS AND CALLOSE OF POLLEN IN PINUS MASSONIANA LAMB
Xiao De-xing (Department of Botany, Agricultural University of Jiangxi
The present paper describes the distribution of starch grains and the deposition of callose during microsporogenesis and pollen development in Pinus massoniana Lamb. During prophase- Ⅰ, starch grains are distributed in the peripheral cytoplasm of the pollen mother cell (PMC). After meta-phase- Ⅰ, the starch grains are gradually aggregated in the equatorial region. Before entering the third mitosis, the cells do not accumulate starch grains. After vegetative and generative cells are formed, only the vegetative cells may accumulate starch grains rapidly. During prophase- Ⅰ, callose first ap- pears between the cell wall and plasmic membrane of PMC. From telophase- Ⅰ to prophase- Ⅱ , a ring-shaped callose is formed around the middle of PMC. Two half ring-shaped calloses appear at the sides of PMC at telophase- Ⅱ. During the pollen development in Pinus massoniana, it is noteworthy that before entering the first mitosis, the cytoplasm of pollen is completely enclosed by callose wall and it may devide only after disappearing of the callose at the germ furrow. Both the primary prothallial cells and generative cell are obviously enclosed by the callose wall, but the primary prothallial cells are enclosed in longer time.