Climate ready rice: Optimising transpiration to protect rice yields under abiotic stresses

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).

This project aims to improve stress tolerance in rice, an important food crop both in Asia and around the world. To achieve this we have reduced the number of stomata that develop on rice leaves. As these are the major routes for water loss from the plant, we expect these plants to have enhanced drought tolerance and water use efficiency. Conversely we expect plants with increased stomatal development to have enhance capacity for cooling at high temperatures. To test these ideas we will use genetically modified plants but part of our project is aimed at identifying non-GM rice with the same traits, and additional genes involved in the same developmental pathway. Drought, water use efficient or heat tolerant rice would have an important economic impact for farmers, in Asia and in drought and heat prone areas of the world, and could help prevent fluctuations of prices on world markets and improve food security.

In addition to being a major global crop, rice and is generally regarded as an important cereal for direct human consumption (rather than for livestock feed) and the most significant global source of vegetable carbohydrate. Drought tolerance and water use efficiency are key crop traits which are becoming increasingly significant as water resources are limited and the human population continues to rise.

This project will build and strengthn links between the plant science research group at the University of Sheffield and rice geneticist and crop scientists at the International Rice Reaearch Institute (IRRI) in the Philippines, the Rice Science Center at Kasetsart University in Thailand, and the Biotechnology Research Institute of Chinese Academy of Agricultural Sciences (CAAS). It will therefore provide new routes for Arabidopsis model-to-crop translational research through the Newton programme.

The postdoctoral researcher and technician carrying out the research in UK will gain advanced skills in plant physiology and crop science, important for meeting the challenge of global food security, an RCUK cross-council priority area. The researcher will have access to the Faculty of Science 'Think Ahead' training programme; winner of the 2014 THES Outstanding Support for Early Career Researchers prize.