RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan.
Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara 630-0192, Japan.
Genes (Basel). 2021 Jun 8;12(6):885. doi: 10.3390/genes12060885.
The plant hormone abscisic acid (ABA) is actively synthesized in vascular tissues and transported to guard cells to promote stomatal closure. Although several transmembrane ABA transporters have been identified, how the movement of ABA within plants is regulated is not fully understood. In this study, we determined that Arabidopsis NPF4.6, previously identified as an ABA transporter expressed in vascular tissues, is also present in guard cells and positively regulates stomatal closure in leaves. We also found that mutants defective in NPF5.1 had a higher leaf surface temperature compared to the wild type. Additionally, NPF5.1 mediated cellular ABA uptake when expressed in a heterologous yeast system. Promoter activities of were detected in several leaf cell types. Taken together, these observations indicate that NPF5.1 negatively regulates stomatal closure by regulating the amount of ABA that can be transported from vascular tissues to guard cells.
植物激素脱落酸（ABA）在维管束组织中被积极合成，并被运输到保卫细胞以促进气孔关闭。尽管已经鉴定出几种跨膜 ABA 转运蛋白，但植物内 ABA 的运动如何被调节还不完全清楚。在这项研究中，我们确定先前被鉴定为在维管束组织中表达的拟南芥 NPF4.6 也存在于保卫细胞中，并正向调控叶片中的气孔关闭。我们还发现，与野生型相比，NPF5.1 缺陷突变体的叶片表面温度更高。此外，NPF5.1 在异源酵母系统中表达时介导细胞内 ABA 的摄取。在几种叶片细胞类型中检测到 的启动子活性。综上所述，这些观察结果表明，NPF5.1 通过调节可以从维管束组织运输到保卫细胞的 ABA 量来负向调控气孔关闭。
