Role of potassium transport in rice in securing high crop yields.

• Applicant: Professor Dr. Rob Roelfsema, Ph.D.
• Subject Area: Plant Physiology ; Plant Biochemistry and Biophysics ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445975641

Cereals in general, and rice in particular, are the major source of nutrition for a growing world population. Many of these crops are grown at intensively utilized fields, in which soil nutrients need to be constantly resupplied by fertilization. Because of the high costs and energy demand, there is a need to reduce the use of fertilizers and adapt to a more sustainable form of agriculture. Crop plants that use nutrients more efficiently than the currently available lines, can help to reach these future goals. Potassium (K+) is the most important cationic nutrient and its transport has been studied intensively for the model plant Arabidopsis., but little is known about the transport proteins that channel K+ fluxes in the cereals. Our previous study has revealed important differences in tissue localization and activation mechanisms of K+ efflux channels, between rice plants and Arabidopsis. In the proposed project we will focus on Shaker type K+ efflux channels and HAK/KUP K+ efflux transporters, which enable transport of K+ from the root to the shoot of rice plants and within the stomatal complexes in the leaves. We will pinpoint the cell types in which the selected K+ transport proteins are expressed and generate rice plants that lack functional versions of these proteins. These transgenic lines will be compared with wild type rice plants, for their ability to grow, consume water and produce crop yield, at green house and field conditions. Moreover, we will use Arabidopsis guard cells and Xenopus oocytes to express the rice K+ efflux channels and transporters and characterize their biophysical properties, like ion selectivity and voltage-dependent activation. The specific roles of the selected K+ channels and transporters in xylem function and stomatal movements will be at the centre of our attention. We will introduce fluorescence-tagged versions of the K+ channels and transporters to study if the transport proteins show a polarized subcellular localization. The specific roles of these transporters will be further uncovered with single cell techniques, in which ion selective electrodes are applied. Our studies will provide insights into the functions of specific K+ efflux channels and transporters at the cellular level, as well as their importance for growth of rice plants at field conditions. It is likely that this knowledge will be valuable for breeding rice plants with a lower demand for K+ fertilizers, while maintaining a good nutritional quality of the grains. Such traits will be of prime importance for sustainable agriculture and future food security.

• DFG Programme: Research Grants
• International Connection: France
• Partner Organisation: Agence Nationale de la Recherche / The French National Research Agency
• Co-Investigators: Professor Dr. Dietmar Geiger; Professor Dr. Rainer Hedrich
• Cooperation Partners: Dr. Jean-Christophe Boyer; Dr. Claire Corratgé-Faillie; Dr. Doan Trung Luu; Dr. Anne-Aliénor Véry