背景回顾：The effects of abscisic acid (ABA) on plant growth, development, and response to the environment depend on local ABA concentrations. 

主要发现：Here, we show that in Arabidopsis, ABA homeostasis is regulated by two previously unknown ABA transporters. 

结果1-蛋白定位及功能：Adenosine triphosphate–binding cassette subfamily G member 17 (ABCG17) and ABCG18 are localized to the plasma membranes of leaf mesophyll and cortex cells to redundantly promote ABA import, leading to conjugated inactive ABA sinks, thus restricting stomatal closure.

结果2-基因敲除：ABCG17 and ABCG18 double knockdown revealed that the transporters encoded by these genes not only limit stomatal aperture size, conductance, and transpiration while increasing water use efficiency but also control ABA translocation from the shoot to the root to regulate lateral root emergence. 

结果3-胁迫条件：Under abiotic stress conditions, ABCG17 and ABCG18 are transcriptionally repressed, promoting active ABA movement and response. 

结论：The transport mechanism mediated by ABCG17 and ABCG18 allows plants to maintain ABA homeostasis under normal growth conditions.

 摘 要 

脱落酸（ABA）对植物生长、发育和环境响应的影响取决于植物自身的ABA浓度。本文中，作者的研究发现在拟南芥中，ABA内稳态受到两种以前未知的ABA转运蛋白调控。三磷酸腺苷结合盒亚家族G成员ABCG17和ABCG18定位于叶肉细胞和皮层细胞的质膜，以冗余的方式促进ABA的输入，导致结合态的非活性ABA库，从而限制气孔关闭。ABCG17和ABCG18双敲减实验表明，这些基因编码的转运蛋白不仅能够在提高水分利用效率的同时，限制气孔孔径大小、电导率和蒸腾作用，而且还能够控制ABA从地上部分向根的转运，以调节侧根的形成。在非生物胁迫条件下，ABCG17和ABCG18被转录抑制，促进活性ABA的移动和响应。ABCG17和ABCG18介导的转运机制使得植物能够在正常生长条件下维持ABA的内稳态。

 通讯作者 

** EILON SHANI **