A cytological study on comparison of anther and pollen development in male-sterile and corresponding maintainer lines in Chinese onion

In order to investigate the mechanism of leek male sterility, a comparative study on anther and pollen development process in Chinese onion (Allium fistulosum L.) was carried out between the male sterile (MS) line and its corresponding maintainer (M) line by means of paraffin section. The result showed that the microspore mother cell of male sterile line could pass through meiosis and form tetrads and then tetrads could release microspore as the same as fertile line. The abortion of microspore occurred at the mono-nucleus microspore (MNM) stage,which had the characteristics of the MNM abortion. Two types of pollen abortion were observed in male sterile line by light microscope:(1)The tapetum could develop normally,but the middle layer still existed at MNM stage,the microspores were squeezed into a deep dyed conglomeration owning to the shrinking powder chamber;(2)The tapetum of male sterile line degenerated before fertile line,so as not to provide enough nutrition for microspore's development,the protoplast and nucleus of microspore degraded in succession and just left the empty pollen wall at last.