Pollen diffusates of Crotalaria retusa and their role in pH regulation

Abstract

Details of the release of proteins and amino acids from cultured pollen grains and the role of the leached metabolites in pollen germination, pollen tube growth and regulation of pH of the culture medium in Crotalaria retusa have been investigated. In unbuffered media, satisfactory pollen germination and tube growth occurred over a wide range of pH values 4.0-9.0. This was related to the ability of pollen diffusates to shift the pH to 6.25 in all these media. Similar pollen germination and pH shift was observed when the pollen was eluted twice before culturing. When the pH shift was reduced by using buffered media, optimal germination and tube growth occurred only at pH 6.0. Pollen diffusates had a strong buffering capacity. Proteins and amino acids released from pollen do not seem to have a direct role in pH regulation. The components involved in pH regulation may originate from the pollen wall as well as from the cytoplasm.