Integrated molecular basis of nitrogen and phosphate signal networks in rice.

氮、磷是水稻最重要的营养元素。然而，过量的氮、磷肥投入对环境造成了不良影响。因此，高氮、高磷利用率品种的遗传育种是农业生产上的一项重要策略。在这项研究中，我们表明，类NIN蛋白OsNLP 3是最接近的同源物AtNLP 7。在单一硝态氮条件下，osnlp3突变体株系表现出明显的生长迟缓，尤其是在高硝态氮条件下，其地上部长度和生物量均明显下降。OsNLP3基因的缺失抑制了一系列硝酸盐转运蛋白和硝酸盐同化基因的表达。此外，在高硝酸盐和低硝酸盐条件下，osnlp3突变体的N含量也比WT降低，表明OsNLP 3负责水稻苗期的硝酸盐依赖性生长。与拟南芥AtNLP 7的情况一样，OsNLP 3表现出硝酸盐促进的核质穿梭现象。田间试验结果表明，在低氮和高氮条件下，osnlp3均表现出穗数和粒数减少。更有趣的是，osnlp3突变体在低磷条件下显示出比野生型明显更短的根长。我们的研究表明，OsNLP 3是氮运输和利用的关键调节因子，也可能参与硝酸盐和磷酸盐有效性的微调。因此，OsNLP 3基因可作为今后高氮利用效率水稻品种遗传育种的潜在目标。

N and P were two of the most important nutrient in rice. However, excess N and P fertilizer input caused deleterious effects on environment. Therefore, genetic breeding of high NUE and PUE cultivars is a desirable strategy in agricultural production. In this study, we show that NIN-like protein OsNLP3 which is the closet homolog of AtNLP7. In the sole nitrate condition, osnlp3 mutant lines exhibited significantly growth retardation compared to the WT which including the decreased shoot length and biomass, especially under high nitrate condition. Loss-of-OsNLP3 suppress a series of nitrate transporter and nitrate assimilatory genes. Moreover, N content of osnlp3 mutant were also reduced compared to the WT under both high nitrate and low nitrate condition, indicating that OsNLP3 is responsible for nitrate dependent growth in rice seedling stage. Like the case of AtNLP7 in Arabidopsis, OsNLP3 exhibited nitrate promoted nucleocytosolic shuttling phenomena. In addition, field trails demonstrate that osnlp3 exhibited decreased panicle number and grain number compared to the WT under both low N and high N fertilizer condition. More interestingly, osnlp3 mutants shows significantly shorter root length compared to the wild type under low phosphate condition. Our study demonstrate that OsNLP3 is a key regulator of N transport and utilization, and may also participate in the fine tuning of nitrate and phosphate availability. Therefore, OsNLP3 could be a potential target for genetic breeding of high NUE rice cultivars in the future.