India-UK Nitrogen Fixation Centre (IUNFC)

Nitrogen is an essential element of biological molecules and life on earth. Lack of usable nitrogen limits growth of microbes, plants, and animals. Lack of nitrogen in agricultural soils limits plant production of food, feed, fibre and fuel. Nature solved the nitrogen limitation problem via evolution of biological nitrogen fixation (BNF) in diazotrophic bacteria that reduce atmospheric N2 to NH3, which is readily assimilated into biological molecules. Biological nitrogen fixation is catalyzed by a complex metalloenzyme called nitrogenase whose oxygen-sensitivity may explain its restricted distribution amongst prokaryotes. Some plants, including most legumes and a few non-legumes form intimate, nitrogen-fixing symbioses with diazotrophs that provide the plants with ammonia. As a consequence, legumes have been an integral part of sustainable agricultural systems for thousands of years. However, in an effort to increase plant yields large-scale use of industrially-produced N-fertilizer has doubled the influx of N into the terrestrial biogeochemical N-cycle, with serious negative consequences for human health and the natural environment. Therefore, the long-term sustainability of massive N-fertilizer inputs in agriculture has come into question. A team of eight investigators in India and two in the UK have come together to enhance the use of legumes, increase their effectiveness at fixing nitrogen and develop endophytic diazotrophs for use on cereals such as rice. Our focus is on pigeon pea, which is the second most widely planted legume in India but suffers from poor rates of BNF and low yields. We will select elite lines of pigeon pea and competitive rhizobial inoculants to maximise yields while improving their robustness. In addition we will develop phosphate solubilising strains of rhizobia as the supply of phosphorous often limits the rates on BNF and plant yield. Desirable traits for BNF and phosphate solubilisation will then be stacked into rhizobial inocula. A final long-term aim is the transfer of BNF to cereals, particularly rice, by the use of endophytic diazoptophs that can be inoculated onto cereals. This will be done both by selection of new endophytic diazotrophs and by manipulation of the control of BNF and ammonia secretion in elite strains. To achieve these aims we bring together the national leaders in India and the UK with expertise in bacterial and plant genetics, genomics, biochemistry, molecular and cell biology, physiology, synthetic biology combined with a deep knowledge of BNF in Indian soils and different regions. Improving BNF in our target plants will increase croyields for resource-poor farmers while decreasing the use and environmental-impact of industrial N-fertilizers.