Biological Faculty, M.V.Lomonosov Moscow University, Vorob'evy Gory, Moscow 119899, Russia

Abstract

The results of recent investigations considerably extend the knowledge of microsporangium stage of male haploid phase. Thus it became clear that tapetum regulate pollen grain formation. The role of cytoskeleton in the development of microspore and its polarity during preparation for asymmetric mitoses is studied. The special systems of microtubes that participate in these processes are revealed, and the genes that are specific for microspore and vegetative cell of a pollen grain are discovered. It is shown that expression of genes controlling the development of vegetative cell and gametophyte function does not depend on microspore mitoses and is activated without participation of generative cell. The authors present some new arguments in understanding of multistage mechanism of recognition between pollen grain, pollen tube and pistil. It was determined that on all stages of this process male gametophyte needs adhesive contact with extracellular matrix of pistil tissues. Arabigalaction proteins play a role of adhesive molecules, chemotrophic factors directing the growth of pollen tube were identified among them. The direction of pollen tube growth is regulated by changing in local concentration of free endocellular Ca2+ in some fragments of apical part of pollen tube.