Two citrate transporters coordinately regulate citrate secretion from rice bean root tip under aluminum stress
Two citrate transporters coordinately regulate citrate secretion from rice bean root tip under aluminum stress
复制标题
铝胁迫下两种柠檬酸转运蛋白协调调节米豆根尖柠檬酸分泌
DOI：
10.1111/pce.13150
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发表时间：
2018-04-01
影响因子：
7.3
通讯作者：
Yang, Jian Li
中科院分区：
文献类型：
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作者：
Liu, Mei Ya;Lou, He Qiang;Yang, Jian Li
铝（Al）诱导根尖分泌有机酸是一种重要的抗铝机制。然而，植物如何微调根部有机酸的分泌仍不清楚，这可能对植物固定碳的损失起重要作用。本研究表明，铝诱导的水稻豆根尖分泌柠檬酸盐是两期的，前期分泌量少，后期分泌量大。我们分离并鉴定了VuMATE2作为水稻豆荚中与VuMATE1串联起作用的第二个可能的柠檬酸转运蛋白。VuMATE2表达的时间依赖性动力学与早期根分泌柠檬酸盐的动力学密切相关。VuMATE2在拟南芥中的异位表达导致根部柠檬酸盐分泌增加和铝抗性增强。对表达VuMATE2的爪蟾卵母细胞电生理分析表明，VuMATE2介导阴离子外排。然而，VuMATE2的表达调控与VuMATE1不同。蛋白翻译抑制剂抑制al诱导的VuMATE1表达，同时释放VuMATE2表达。酵母单杂交实验表明，先前鉴定的转录因子vusstop1在GGGAGG顺式作用基序上与VuMATE2启动子相互作用。因此，我们证明植物通过两个独立的根柠檬酸盐运输系统微调根柠檬酸盐分泌来适应铝毒性。
Aluminum (Al)-induced organic acid secretion from the root apex is an important Al resistance mechanism. However, it remains unclear how plants fine-tune root organic acid secretion which can contribute significantly to the loss of fixed carbon from the plant. Here, we demonstrate that Al-induced citrate secretion from the rice bean root apex is biphasic, consisting of an early phase with low secretion and a later phase of large citrate secretion. We isolated and characterized VuMATE2 as a possible second citrate transporter in rice bean functioning in tandem with VuMATE1, which we previously identified. The time-dependent kinetics of VuMATE2 expression correlates well with the kinetics of early phase root citrate secretion. Ectopic expression of VuMATE2 in Arabidopsis resulted in increased root citrate secretion and Al resistance. Electrophysiological analysis of Xenopus oocytes expressing VuMATE2 indicated VuMATE2 mediates anion efflux. However, the expression regulation of VuMATE2 differs from VuMATE1. While a protein translation inhibitor suppressed Al-induced VuMATE1 expression, it releases VuMATE2 expression. Yeast one-hybrid assays demonstrated that a previously identified transcription factor, VuSTOP1, interacts with the VuMATE2 promoter at a GGGAGG cis-acting motif. Thus, we demonstrate that plants adapt to Al toxicity by fine-tuning root citrate secretion with two separate root citrate transport systems.