In vitro protein synthesis in isolated microspores of Zea mays at several stages of development.

A new procedure has been used providing large and homogenous populations of pollen from maize at different stages of their development. In order to label proteins synthesized during the course of microsporogenesis, a method has been developed that allows an efficient uptake of amino acids in the microspores. Results are presented showing that during pollen development three specific steps are involved: an early period active in protein synthesis, followed by a rest period when starch is accumulated, and a third period preceding the sorting out of mature pollen grains and during which protein synthesis starts again at a relatively low level. New polypeptides, some of which are very basic, appear at the time of starch deposition and accumulate up to the mature stage.