Total Polysaccharide Content of Developing Pollen in Two Angiosperm Species

The PAS reaction was used to stain total insoluble polysaccharides in whole pollen grains of anthers of Borago officinalis and Lycopersicum peruvianum from early microspore to ripe pollen stage. Total polysaccharide content was quantified with a microdensitometer: in Borago officinalis values showed two peaks, one during the microspore and the other during the binucleate stage; in Lycopersicum, there was a single peak during the latter stage. In both species total polysaccharide content decreased markedly in the last stage of pollen development before anthesis, when starch was hydrolysed and the polysaccharide reserves of the pollen transferred to the cytoplasm. Pollen grain volume was also determined at the various stages. It was found to increase, though with a different pattern in the two species, and to decrease before dehiscence. The results are discussed in terms of cytoembryological data of pollen grain development.