NRT1.2 has been characterized as a low-affinity nitrate transporter and an abscisic acid (ABA) transporter in Arabidopsis. In this study, we demonstrate that NRT1.2 positively regulated the ABA response during germination and seedling development. The transgenic Arabidopsis NRT1.2-over-expressionors showed increased sensitivity to ABA during these processes. qRT-PCR assays indicated that NRT1.2 over-production in 7-days-old seedlings up-regulated the expression of ABA-responsive genes: ABI1, ABI2, ABI3, ABI4, ABI5, RAB18, RD29A, and RD29B and PHOSPHOLIPASE Dα1 (PLDα1). The expression of these genes was suppressed in the nrt1.2 mutant in comparison with the wild type following ABA treatment. Importantly, bimolecular fluorescence complementation assays indicated that NRT1.2 interacts with PLDα1 at the plasma membrane. Their interaction was further confirmed by using yeast two hybrid (Y2H) experiments with the mating-based split ubiquitin system (MbSUS). Moreover, genetic assays indicated that PLDα1 acts epistatically on NRT1.2 to affect ABA signaling. Taken together, our results provide detailed mechanisms of NRT1.2 in ABA-mediated seed germination and seedling development.

NRT1.2已被表征为拟南芥中的低亲和力硝酸盐转运蛋白和脱落酸（ABA）转运蛋白。在这项研究中，我们证明NRT1.2在发芽和幼苗发育过程中积极调节ABA的响应。在这些过程中，转基因拟南芥NRT1.2过表达子显示出对ABA的敏感性增加。qRT-PCR分析表明，在7天大的幼苗中NRT1.2的过量生产上调了ABA响应基因的表达：ABI1，ABI2，ABI3，ABI4，ABI5，RAB18，RD29A和RD29B和PHOSPHOLIPASEDα1（PLDα1）。与ABA处理后的野生型相比，在nrt1.2突变体中这些基因的表达受到抑制。重要的是，双分子荧光互补分析表明NRT1.2与质膜上的PLDα1相互作用。通过将酵母与基于交配的分裂泛素系统（MbSUS）进行的两个杂交（Y2H）实验，进一步证实了它们的相互作用。此外，遗传分析表明，PLDα1上位互作作用在NRT1.2影响ABA信号。两者合计，我们的结果提供了NRT1.2在ABA介导的种子发芽和幼苗发育中的详细机制。