氮素是作物必需的营养元素之一，对作物的生命活动和产量的形成具有重要意义。近年来，随着农田氮肥的过量施用，对环境造成的污染也日益加重。提高作物氮利用效率，是农业可持续发展的关键，是第二次“绿色革命”的目标和要求。
中科院华南植物园植物营养生理研究组博士研究生方中明在张明永研究员的指导下，发现在水稻中超表达OsPTR9基因可促进水稻对铵态氮的吸收，同时在低施氮肥的条件下可促进水稻增产。研究显示：OsPTR9基因的表达受外界氮源和光昼夜节律的调节。营养生长阶段，超表达OsPTR9能够促进铵的吸收，增加侧根的发生，提高水稻生物量。生殖生长阶段，超表达OsPTR9能够提高氮再动员和重新分配的运输效率，最终提高水稻产量。在OsPTR9降低表达的突变体和RNAi植株中指标和表型相反。在不施氮肥的种植下，超标达OsPTR9的水稻的产量比对照增幅最大，达到18.6%；正常施用氮肥下，超表达OsPTR9的水稻两个株系比对照增产7.2%和8.1%；施用铵态氮肥，有利于超表达水稻获得较高的产量。研究结果初步表明：OsPTR9在促进氮利用效率和水稻分子育种上具有潜在的应用价值，该基因超表达后能够提高土壤中氮的利用，促进水稻生长并提高产量。
该研究成果已申请一项国家发明专利（专利号：201110022987.3），申请并公开一项国际发明专利(专利号：PCT/CN2011/082100)。同时已在国际学术刊物Plant Biotechnology Journal(doi: 10.1111/pbi.12031，IF2011= 5.442)上发表。(生物谷Bioon.com)
DOI: 10.1111/pbi.12031
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Altered expression of the PTR/NRT1 homologue OsPTR9 affects nitrogen utilization efficiency, growth and grain yield in rice
Zhongming Fang1,2,†, Kuaifei Xia1,3, Xin Yang1,2, Marianne Suter Grotemeyer4, Stefan Meier4, Doris Rentsch4, Xinlan Xu3, Mingyong Zhang1,3,*
The plant PTR/NRT1 (peptide transporter/nitrate transporter 1) gene family comprises di/tripeptide and low-affinity nitrate transporters; some members also recognize other substrates such as carboxylates, phytohormones (auxin and abscisic acid), or defence compounds (glucosinolates). Little is known about the members of this gene family in rice (Oryza sativa L.). Here, we report the influence of altered OsPTR9 expression on nitrogen utilization efficiency, growth, and grain yield. OsPTR9 expression is regulated by exogenous nitrogen and by the day-night cycle. Elevated expression of OsPTR9 in transgenic rice plants resulted in enhanced ammonium uptake, promotion of lateral root formation and increased grain yield. On the other hand, down-regulation of OsPTR9 in a T-DNA insertion line (osptr9) and in OsPTR9-RNAi rice plants had the opposite effect. These results suggest that OsPTR9 might hold potential for improving nitrogen utilization efficiency and grain yield in rice breeding.
