Mechanism of Pollen Abortion in Cytoplasmic Male Sterile Line of Sunflower

Abstract

The histological and developmental features of anther were studied in the cytoplasmic male sterile (CMS) line of sunflower (Helianthus annuus L.) and compared with its normal counterpart. The anther development in CMS line was more or less similar to that in the normal fertile line till the formation of microspore tetrads. At this stage a significant visual abnormality in the development of CMS anther was noticed in the form of abnormal enlargement of tapetal cells. Apart from the marked hypertrophy of the tapetal cells some of the radial walls of the cells were partly degenerated forming a coenocytic structure and the nuclei aggregated in the invaded region. The results from the present study has provided further supportive evidence in CMS anthers that the malfunctioning of tapetum is the predominant cause for the abortive process but the abnormality may take many forms and operate at different times.