Pollen and its coat – ‘smart’ dressing for the mating game

The earliest steps of plant reproduction involve an intimate interaction between male and female reproductive structures namely the pollen grain, a vehicle for delivering sperm, and the surface of the stigma which ‘screens’ incoming pollen for compatibility. The establishment of the pollen-stigma interaction is proposed to involve a basal compatibility system that enables compatible pollen to be recognised by the receptive stigma. A key aspect of the work in our lab has been focussed on identifying the signals carried on the surface of pollen (in the pollen coat) that permit stigmas to respond in the appropriate manner to potential partners (partners could be from the same or different species). Through proteomic analysis across three species of the Brassicacaeae (Arabidopsis thaliana, Arabidopsis lyrata and Brassica oleracea) we have uncovered an extraordinary diversity of small cysteine-rich proteins that make up a significant proportion of the pollen coat proteome. Studies to date indicate that several of these small proteins play a role in the initial molecular conversation between pollen and stigma. Our goal is to describe the pollen coat proteome and functionally characterise these proteins with the ultimate goal of identifying their molecular targets in female reproductive tissues.