Cytoplasmic male sterility in barley II. Physiology and anther cytology of msml

The cytoplasmic male sterile, msml (male sterile maternal 1), of barley was studied along with the restored form and with the nearly isogenic normal barley. Under light microscopy and TEM, the male sterile was found to have an abnormally productive and uncontrolled secretion of sporopollenin in its anthers. The energy of the anther is probably wasted in the biosynthesis of sporopollenin precursors. Consequently, several abnormalities are discernable in the cytological appearance of the anther at different developmental stages. The sporopollenin of the male sterile or partially restored male sterile displays a Fast blue B stainability different from that of the normal type. As a result of several observations, the msml stock would appear to be a plastid mutant. In the leaf of the unrestored male sterile plant the ratio of xanthophylls to β‐carotene is about one tenth higher than that of the fertile plant. The restored msml plants were found to have a somewhat higher proportion of chlorophyll b in their chlorophylls than the unrestored material. The male sterile was found to be affected by the Helminthosporium maydis race T toxin in a way similar to that of the normal barley. This male sterility is expected to be beneficial to hybrid breeding of barley.