Mechanism of 2n pollen occurring in Chinese white poplar.
Kang Xiangyang. College of Biological Science and Biotechnology,Beijing For. Univ.,100083, P.R.China.
It was observed that normal diploids of Chinese white poplar (Populus tomentosa Carr.) could produce a certain proportion of bigger pollen grains, which depended on the genotypes and environment. The maximum of the proportion could be up to 14.3%.These bigger pollen grains contained 38 chromosomes by microscope checking. The occurring of 2n pollens in Chinese white poplars was resolved by the heterology genetic basis. The results to absolved meiosis of pollen mother cells (PMC) and pollens showed: the pre meiosis of Chinese white poplar was normal; nuclear restitutions have not been found in the first and second meiosis too; the direction of spindles in metaphaseⅡ were abnormal, i.e. besides of vertical and 60°angle spindles, there were 12.9%～33.7% parallel spindles in the period; moreover, there were some abnormal pollens belong with cytoplasm division abnormal that two or three pollens sticking together. It showed clearly that 2n pollens were produced by parallel spindle fusion, and the cytoplasm division abnormal because of the disorder were aroused in the process of formal cell wall by parallel spindles.