Control of male germ-cell development in flowering plants

Plant reproduction is vital for species survival, and is also central to the production of food for human consumption. Seeds result from the successful fertilization of male and female gametes, but our understanding of the development, differentiation of gamete lineages and fertilization processes in higher plants is limited. Germ cells in animals diverge from somatic cells early in embryo development, whereas plants have distinct vegetative and reproductive phases in which gametes are formed from somatic cells after the plant has made the transition to flowering and the formation of the reproductive organs. Recently, novel insights into the molecular mechanisms underlying male germ-line initiation and male gamete development in plants have been obtained. Transcriptional repression of male germ-line genes in non-male germ-line cells have been identified as a key mechanism for spatial and temporal control of male germ-line development. This review focuses on molecular events controlling male germ-line development especially, on the nature and regulation of gene expression programs operating in male gametes of flowering plants.