Stomata are microscopic pores on the surface of leaves that allow gas exchange between plants and the atmosphere. They are crucial for photosynthesis, but much water vapour is lost by transpiration through leaf stomata. When water is limiting, the stomatal pores adjust to prevent water loss but they can never completely close. We have shown with the model plant Arabidopsis thaliana that reducing the number of stomata can improve plant drought resistance by reducing water loss through transpiration, and help to conserve the amount of water in soils. Conversely, increasing the number of stomata enhances evaporative cooling and would be expected to increase tolerance to heat stress. We would like to apply this strategy to rice so that we can test whether reducing stomatal numbers could improve crop drought and heat stress tolerances, both increasingly major limitations to yield in many parts of the world. We will carry out experiments that aim to re-direct plant water loss to allow enhanced evaporative cooling in reproductive organs without compromising plant drought tolerance, which could be important in future hot and dry environments and at higher atmospheric carbon dioxide concentrations. We have already generated rice plants with genetically reduced or increased stomatal numbers, and propose to test whether growing these under drought or high temperature conditions can improve the total yield of grain harvested. These experiments will be performed on genetically modified (GM) plants but we also propose to isolate and study rice variants in genes that are involved in stomatal development through non-GM techniques, and include these in our studies and test them for drought and heat resistance. We believe that our work will be strategically relevant to the production of rice crops with enhanced drought and heat stress tolerance, and an important step towards improving food security across Asia. Our project directly addresses the following aims of the Newton Rice Research funding scheme: - Greater resilience to abiotic stresses (in this project drought and heat stresses). - Improved resource use efficiency (in this project enhanced water use efficiency). - Novel research tool and technology development (in this project screening and characterisation of germplasm for gene and trait discovery).