硝酸盐转运蛋白OsNRT2.3b参与调控水稻吸收转运菲的机制研究

土壤中的多环芳烃（菲）可被作物吸收转运进入食物链，然而关于这一过程的机制研究甚少。硝态氮能够抑制作物根对菲的吸收，这可能与硝态氮和菲吸收均可改变pH有关。申请人初步研究发现，硝酸盐转运蛋白OsNRT2.3b参与调控水稻吸收转运菲，推测一方面是由于OsNRT2.3b超表达改变了根际pH，另一方面其含有的细胞pH感受位点H167在起作用。本项目拟用三种不同基因型水稻材料（OsNRT2.3b超表达、突变H167的OsNRT2.3b超表达及OsNRT2.3a超表达）在菲、pH、氮处理下，通过水培测定根部菲含量，通过微电极法检测根细胞膜电位变化，明确OsNRT2.3b如何通过调节pH调控菲的吸收；通过水培和/或桶培实验测定水稻各项指标，揭示OsNRT2.3b通过调节pH调控菲的转运、再分配以及籽粒累积的迁移过程及机制。研究结果将为氮素管理和基因工程增强作物阻控菲的能力提供依据。

Polycyclic aromatic hydrocarbons (PAHs, phenanthrene) in the soil enter the food chain though the uptake and translocation by crops. However, there are few studies on this process and its mechanism. It is reported that nitrate can inhibit the absorption of phenanthrene by crop roots, which is possibly related to the fact that both nitrate and phenanthrene absorption can change pH. The applicant’s preliminary study found that rice nitrate transporter OsNRT2.3b is involved in the regulation of phenanthrene uptake and transport in rice. It is speculated that on the one hand, overexpression of OsNRT2.3b changes the rhizosphere pH. On the other hand, it contains the cytosolic pH-sensing site H167. To investigate the mechanism behind this phenomenon, we will use three different genotypes of rice materials, including OsNRT2.3b overexpressing, OsNRT2.3b-H167R mutant-overexpressing and OsNRT2.3a overexpressing lines, to carry out the research in this proposal. Under different phenanthrene, pH and nitrate treatments, first, in the hydroponic system, the phenanthrene concentration in the roots will be assayed and the membrane potential change of the root cells during the phenanthrene uptake will be detected by microelectrode, to clarify how OsNRT2.3b regulates the absorption of phenanthrene by adjusting pH. Second, various experimental parameters will be measured and analyzed to reveal the process and mechanism of OsNRT2.3b regulating the phenanthrene translocation, redistribution and accumulation in grain by adjusting pH. This study will provide theoretical basis for enhancing the ability of crops to prevent phenanthrene through reasonable nitrogen management and plant genetic engineering.