Male sterile mutants of barley

Some enzymes of the microspores of normal barley plants and the msg6cf mutants were studied by histochemical means. The mutant has previously been shown to produce inaperturate pollen. Acid phosphatases and esterases were studied during successive stages of development. These enzymes could be divided into early and late types. An early acid phosphatase and an early and a late esterase seem to be associated with the formation of the aperture, or germ pore. The late poral esterase is evidently capable of hydrolyzing sporopollenin or pro‐sporopollenin. It was localized in the membrane layer under the pore. This layer was studied with TEM. The late esterase is present in the mutant pollen also. It seems that the early ontogeny of the pore is changed in the mutant. The exine and some other structures containing sporopollenin were shown to be stained with diazonium salts, and also, at one stage, with hexazotized pararosaniline. Fast blue B salt was found to be coupled with a high specificity by these structures. Different types of sporopollenin were revealed by this staining, which is also suitable for fluorescence microscopy. The observations on the exine are discussed in relation to the esterase activity present on the microspore surface.