Cytological Observation of Anther Development of an Ecological Male Sterile Line H50S in Brassica napus L.

H50S is an ecological male sterile accession which was found in a cultivar named Huiyou 50 from Shanghai.Cytological observation by squashing and paraffin section method revealed that H50S anther abortion started from the early monocyte stage.Triangular thickening was not obvious in the late monocyte.Moreover microspore mother cells,metaphase I and tetrads were all simultaneously observed in a single anther.Paraffin section results confirm the microspore abortion characteristics of squashing results.Anther development of H50S could pass through the meiosis stage and normal tetrads could be formed in H50S.After microspores releasing from the tetrads,abortion of microspores begin.No obvious vacuole could be found in the aborted microspores and nuclei of the aborted microspores collapsed.At the mature stage,Wall of aborted microspores could be developed,however degeneration of tapetum was delayed.Finally,sterile pollen grains only remained shell.A synchrony of microspore development was observed within a single anther.