Cytoplasmic Male Sterility

Abstract

Cytoplasmic male sterility (CMS) is a commonly observed phenotype in higher plants, where it is described in over 140 plant species (Laser and Lersten, 1972). Viable pollen is not produced by plants exhibiting the cytoplasmic male sterility trait. Although all CMS plants are alike in that they are unable to produce viable pollen, the specific mechanism differs among plant species. For instance, pollen abortion in the S cytoplasm (cms-S) of maize takes place late in development when nearly mature pollen grains abruptly abort. Pollen abortion occurs earlier in development in the Texas cytoplasm (cms-T) of maize than in cms-S. Precocious degeneration of the tapetal cell layer of the anther is implicated in the failure of pollen development in cms- T (Warmke and Lee, 1977; Lee and Warmke, 1979). CMS of tobacco is unusual in that development of the male flower parts is often drastically altered. Anthers from the tobacco repanda CMS become stigmalike, an event that suggests feminization of the anther (Gerstel, 1980). Another CMS of tobacco, undulata, is caused by stamens becoming petaloidlike rather than developing into normal stamens terminated by anthers. The extensive variation among CMS indicates that distinct and diverse factors are responsible for the male sterility trait. Moreover, the effect is apparently limited to pollen development because female fertility is generally unaffected by CMS.KeywordsMitochondrial GenomeCytoplasmic Male SterilitySomatic HybridProtoplast FusionRestorer GeneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.