Anatomical and Histochemical Studies on Pollen Degeneration in CMS Helianthus petiolaris Nutt.

The purpose of this microscopic histochemical study was to establish the developmental sequence leading to sterility in a cytoplasmic male sterile Helianthus petiolaris line. Histochemical studies showed that CMS anthers, in contrast to fertile anthers, lacked carbohydrate storage at sporogenous stage. CMS sporogenous cells were thick-walled and ascorbic acid-rich. Subsequent developmental pattern was not uniform in CMS anthers. The variations were found in different anthers and in different locules of the same anther. Two categories of CMS anthers lacked callose deposition and showed premature disintegration of tapetal cell layer, which lead to precocious formation of periplasmodium. In one type, CMS anthers contained naked microspores. In another type, coenocytic microspores were formed. The microspores lacked reserve metabolites. In the third category of CMS anthers normal callose deposition and tetrad formation were observed. In this category callose deposition and hypertrophied tapetal cell layer persisted until mature stage of the anther. Results in all 3 categories of CMS anthers link tapetal abnormality to male sterility.