India-UK Nitrogen Fixation Centre (IUNFC)

氮是地球上生物分子和生命的基本元素。缺乏可用的氮限制了微生物、植物和动物的生长。农业土壤中氮的缺乏限制了植物生产食物、饲料、纤维和燃料。大自然通过固氮细菌中生物固氮（BNF）的进化解决了氮限制问题，该固氮细菌将大气中的N2还原为NH3，NH3很容易被同化为生物分子。生物固氮是由一种称为固氮酶的复杂金属酶催化的，其氧敏感性可以解释其在原核生物中的有限分布。一些植物，包括大多数豆科植物和少数非豆科植物，与固氮生物形成亲密的固氮共生体，为植物提供氨。因此，数千年来，豆类一直是可持续农业系统的组成部分。然而，为了提高植物产量，工业生产的氮肥的大规模使用已经使进入陆地生态地球化学N循环的N的流入量增加了一倍，对人类健康和自然环境产生了严重的负面影响。因此，农业中大量氮肥投入的长期可持续性受到质疑。一个由印度的8名研究人员和英国的2名研究人员组成的团队聚集在一起，以提高豆类的使用，提高其固氮效率，并开发用于水稻等谷物的内生固氮菌。我们的重点是木豆，这是印度第二大种植豆类，但遭受生物固氮率低和产量低。我们将选择木豆的优良品系和有竞争力的根瘤菌接种剂，以最大限度地提高产量，同时提高其健壮性。此外，由于磷的供应通常限制了生物固氮和植物产量，我们将开发根瘤菌的解磷菌株。然后将生物固氮和磷酸盐溶解的理想性状堆叠到根瘤菌接种物中。最后一个长期目标是通过使用可接种到谷物上的内生固氮菌将生物固氮转移到谷物，特别是水稻。这将通过选择新的内生固氮菌和通过操纵优良菌株中的BNF和氨分泌的控制来完成。为了实现这些目标，我们汇集了印度和英国的国家领导人，他们具有细菌和植物遗传学，基因组学，生物化学，分子和细胞生物学，生理学，合成生物学方面的专业知识，并结合了印度土壤和不同地区的生物固氮知识。在我们的目标植物中提高生物固氮将增加资源贫乏的农民的作物产量，同时减少工业氮肥的使用和对环境的影响。

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.