Tiny pores with a global impact

The transition of plants from sea to terrestrial environments is undoubtedly one of the key steps during evolution. It required formation of a gas-impermeable cuticle and guard cells, which form stomatal pores that act as valves for gas-exchange between plants and surrounding environment. Closed stomata shield aboveground plant tissues from harmful factors, such as drought, air pollution and pathogenic microorganisms. Opening of these microscopic pores allows plants to assimilate vast amounts of the greenhouse gas CO2 and return more than half of the terrestrial rainfall to the atmosphere. Because of these large gas fluxes, stomata are not only of crucial importance for plant growth and agriculture, but also have a major impact on our climate (Fig. 1). No wonder that the function, development and evolution of stomata have attracted the attention of numerous scientists worldwide. TheNew Phytologist Symposium ‘Stomata 2012’ provided a platform for them to discuss recent progress as well as unsolved issues.