POLLEN: AN AMAZING MODEL SYSTEM TO STUDY A DISPARATE SERIES OF PLANT BIOLOGICAL PROCESSES

Abstract

Pollen, the male gametophyte of higher plants, represents an extremely interesting, and peculiar, experimental system for the study of diverse aspects of plant biology, apart from the - obvious - research on gametophytic development in itself. For example, cell cycle progression, as the formation of mature pollen from the microspore mother cells consists in a series of specific, often synchronous cell divisions: meiosis, the asymmetric microspore mitosis and the division of the generative pollen cell. Also, for the study of the interactions between the gametophyte and the sporophyte during pollen development, the formation of the - unusual - pollen wall or intracellular transport processes during pollen tube growth. Instead of dedifferentiating and forming a callus, as normally happens with any isolated plant cell, microspores isolated from the anthers can continue in vitro their normal developmental programme, giving rise to mature, functional pollen. However, triggered by specific stress treatments, microspores and immature pollen grains can switch towards sporophytic development with the formation of (haploid) embryos and plants. These and other unique characteristics of the pollen system will be discussed in this review