水稻低氮胁迫过程中OsNLPs和OsNiR1互作的调控网络和功能解析

Plant NUE (Nitrogen use efficiency), including N uptake, translocation, assimilation, and remobilization,is inherently complex and is governed by multiple interacting genetic and environmental factors. By using next-generation sequencing, we have performed a temporal transcriptome analysis in rice, covering the early, medium and long term of N deprivation as well as N recovery responses in roots and shoots. Analyses of 16 paired-end RNA sequencing libraries, spanning four time points, will provide a comprehensive overview of the dynamic responses of rice to N stress. The transcription factor families important for N starvation and resupply will be analyzed including NIN like transcription family members that induced during all the time points. A target gene regulated by NIN like proteins, OsNiR1 encoding NiR (ferredoxin-nitrite reductase) with NRE (nitrate-responsive cis-element) in the gene promoter, will be characterized as key regulators of N homeostasis in plant.Strikingly, single and double copies of NRE will be investigated in various landraces that affect nitrogen signaling by impacting the expression of OsNiR1.We will present a comprehensive spatio-temporal transcriptome analysis of plant responses to N stress, revealing potential key regulators of plant NUE.

氮素营养是水稻生产重要限制因子，培育氮高效品种，在保持高产稳产同时降低肥料用量具有重要意义。水稻对低氮素胁迫应答过程中，关键基因的转录水平调控对氮素利用效率(NUE)至关重要。我们前期对水稻根和叶短期、中期、长期氮素饥饿和氮素恢复进行转录组动态分析，发现NIN-Like转录因子家族多个OsNLPs成员在4个取样时间点均发生剧烈响应, 暗示OsNLPs在低氮胁迫应答中起关键作用；鉴定了OsNLPs调控下游靶基因亚硝酸还原酶OsNiR1氮素同化基因，直接影响NUE。本项目将进一步（1）研究OsNLPs绑定OsNiR1启动子顺式元件NRE和转录调控OsNiR1的分子机制；（2）明确OsNiR1元件NRE间分子互作及其与低氮响应关系；（3）解析NRE在地方品种群体中差异及其在选择驯化中作用, 阐明OsNLPs和OsNiR1调控网络及其在氮素同化过程扮演的重要角色，具有重要理论意义和实际价值。

氮肥是水稻生长过程中不可或缺的肥料，而氮肥的过量施用会对环境产生不利影响。在低氮下提高水稻的产量是未来可持续农业的育种目标之一。氮素相关转运子的自然编译已有报道，但是氮素同化相关基因在提高氮素利用效率（NUE）中起的作用还鲜有报道。我们利用NUE相关性状通过全基因组关联分析克隆了水稻中一个NIN-like蛋白（NLP4）。我们发现NLP4转录调控水稻中的亚硝酸还原酶OsNiR。接下来通过加倍OsNiR启动子中NLP4的结合位点NRE，我们发现p4xNRE::NiR 转基因家系显著提高氮素利用效率。我们证明了OsNLP4-OsNiR模块通过增强氮素同化能力增加了水稻分蘖数和产量。我们的发现凸显了OsNLP4-OsNiR模块在水稻NUE和产量育种中的作用。