Lipid Accumulation and Related Gene Expression in Gametophytic and Sporophytic Anther Tissues

Abstract

In recent years the ontogenesis and development of the male gametophyte in angiosperms has attracted an increasing interest among plant scientists. The availability of molecular techniques has contributed significantly to unveiling how the expression and regulation of specific classes of sporophytic (tapetal) and gametophytic genes contribute to the formation of a viable pollen grain. Almost a quarter of a pollen grain is made of lipids, which are structural components of both intracellular and extracellular pollen domains. It is not surprising, therefore, that the biogenesis and function of the different lipidic and lipid-derived components has become one of the main areas of interest in sexual plant reproduction. In addition to their structural roles it is becoming clear that lipid-derived molecules are also strongly involved in the pollen-stigma signalling and recognition events. Moreover, lipidic volatiles are released from the pollen coat and act as attractants for pollinators. Whilst the majority of extracellular pollen exine and pollen coat lipid components are synthesised in tapetal cells and relocated to the pollen surface, the majority of pollen intracellular membrane and storage lipids are synthesised within the pollen vegetative cell under the control of the gametophytic genome. The purpose of this Chapter is to review, in the light of a wealth of recent and exciting experimental data, the biogenesis of pollen lipidic structures in tapetal and gametophytic cells and their concerted deposition and function in the assembly of viable pollen grains.