FACTORS AFFECTING IN-VITRO MATURATION OF ISOLATED MAIZE MICROSPORES

An in vitro method to simulate pollen development was developed in mai ze (Zea mays L.). Microspores at the late uninucleate to early binucle ate stage were isolated and cultured under various conditions. Cell vi ability, starch content and the formation of the three nuclei as found in normal mature pollen were monitored during the course of the cultu re. Media composition was modified in order to promote starch accumula tion and frequency of mitosis, while maintaining the viability of the microspores. Under the best conditions, up to 12% of the microspores m atured in vitro into trinucleate, starch-filled viable pollen grains w hich were unable to germinate or produce seeds. At different stages du ring in vitro maturation, proteins patterns were analyzed and compared with their in vivo equivalent and the patterns were only partially si milar.