A comparative study of microsporogenesis and anther wall development in different types of genic and cytoplasmic male sterilities in chives

A new cytoplasmic and two genic male sterilities in chives are compared with male-fertile counterparts for anther development and microsporogenesis. The genic male sterilities (wi and st1) fail to produce viable pollen, since microsporogenesis is stopped around the stage of tetrads. Compared with a previously described cytoplasmic male sterility, CMS1 , which also shows alterations during this stage, wi- and st1-sterile plants fail to produce pollen walls. The last two male sterilities are very similar in development but can be distinguished by the missing breakdown of callose in st1-sterile plants. In contrast to the sterilities described above, the second cytoplasmic male sterility, CMS2 , is caused by functional damages to sporophytic tissues, such as no degeneration of mesothecium cells and no thickening of the endothecial cell walls. These alterations prevent the release of pollen, although they are normally developed.