How rice roots regulate water transport
It is predicted that in the next 20 years almost half of the world will be facing severe water stress. Therefore, plant science technologies should be employed to protect this vital resource by improving water-use efficiency in crops. Rice is a major food crop around the world, but little is known about its aquaporin function and water regulation at the cellular level. The EU-funded 'Cell biology and rice aquaporins' (ORYZAQUA) project addressed these gaps in knowledge in different rice cultivars and changing conditions. Aquaporins are proteins in the plasma membrane of plant cells that act as water channels and are critical to water regulation. Hydraulic conductivity, water permeability and osmotic potential regulation are some of the key factors involved in water regulation in plants. ORYZAQUA researchers studied a range of rice aquaporins, root architecture and hydraulics, and subjected them to salt stress and drought conditions. This was then compared to stress-free conditions. In addition, researchers successfully cloned rice aquaporin sequences and tagged them with fluorescent protein (FP); the transformation of other rice isoforms and cultivars is ongoing. Researchers successfully cloned the fluorescently-tagged OsRabr sequence (aquaporin) for co-expressing endomembrane markers tagged with the mCherry FP. Work was also conducted to express other aquaporin sequences that include OsGAP1 and OsNST1. Studies were also carried out to assess aquaporins' sub-cellular localisation and function in stressed and stress-free conditions in these rice plants. Work conducted by ORYZAQUA established for the first time the strong inhibitory effect of salinity on the root water transport of young rice plants. It showed a physiological mechanism that can respond to environmental challenges within an hour. Since this inhibitory effect is so rapid, it indicates that the regulation of aquaporin activity is a significant factor in whole-plant response to salinity. The project will help explain complex interactions between the molecular pathways for signalling in response to abiotic stress and those controlling cell and organ responses. It will also help to improve agricultural production through better adaptation to climate change and to develop agriculture in marginal lands.
Keywords
Water transport, plant roots, plant science, cell biology, rice aquaporins
