A Defective Vacuolar Proton Pump Enhances Aluminum Tolerance by Reducing Vacuole Sequestration of Organic Acids
A Defective Vacuolar Proton Pump Enhances Aluminum Tolerance by Reducing Vacuole Sequestration of Organic Acids
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有缺陷的液泡质子泵通过减少有机酸的液泡隔离来增强铝耐受性
DOI：
10.1104/pp.19.00626
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Lan W
中科院分区：
文献类型：
--
作者：
Zhang F;Yan X;Han X;Tang R;Chu M;Yang Y;Yang YH;Zhao F;Fu A;Luan S;Lan W
植物通过分泌有机酸（OAs）进入质外体空间来科普铝（Al）毒害，这是由质子（H+）泵驱动的。在此，我们发现液泡H +-ATP酶亚基a2（VHA-a2）和VHA-a3的突变增强了拟南芥（Arabidopsis thaliana）对铝的抗性，vha-a2和vha-a3突变体在过量铝下生长时，表现出较低的铝敏感性和较低的铝积累。Al ~（3+）胁迫下，植物液泡H ~+泵活性降低，VHA-a2和VHA-a3表达减少，质膜H ~+泵（PM H ~+-ATPase）活性增加。对PM H ~+-ATPase活性改变的植物进行遗传分析，确定了Al诱导的PM H ~+-ATPase活性增加与增强的Al抗性之间的相关性。我们确定，外部OAs，如苹果酸和柠檬酸的分泌是由PM H+-ATP酶，增加与PM H+-ATP酶活性铝胁迫。另一方面，苹果酸和柠檬酸根分泌物的分泌升高invha-a2 vha-a3似乎是独立的OAs代谢和耐磷饥饿，但可能与受损的液泡隔离。这些结果表明，液泡H+-ATP酶和质膜H+-ATP酶的协调决定了OAs在液泡腔或质外体空间的分布，从而决定了植物的耐铝能力。
Plants cope with aluminum (Al) toxicity by secreting organic acids (OAs) into the apoplastic space, which is driven by proton (H+) pumps. Here, we show that mutation of vacuolar H+-translocating adenosine triphosphatase (H+-ATPase) subunit a2 (VHA-a2) and VHA-a3 of the vacuolar H+-ATPase enhances Al resistance in Arabidopsis (Arabidopsis thaliana).vha-a2 vha-a3mutant plants displayed less Al sensitivity with less Al accumulation in roots compared to wild-type plants when grown under excessive Al3+. Interestingly, in response to Al3+exposure, plants showed decreased vacuolar H+pump activity and reduced expression ofVHA-a2andVHA-a3, which were accompanied by increased plasma membrane H+pump (PM H+-ATPase) activity. Genetic analysis of plants with altered PM H+-ATPase activity established a correlation between Al-induced increase in PM H+-ATPase activity and enhanced Al resistance invha-a2 vha-a3plants. We determined that external OAs, such as malate and citrate whose secretion is driven by PM H+-ATPase, increased with PM H+-ATPase activity upon Al stress. On the other hand, elevated secretion of malate and citrate invha-a2 vha-a3root exudates appeared to be independent of OAs metabolism and tolerance of phosphate starvation but was likely related to impaired vacuolar sequestration. These results suggest that coordination of vacuolar H+-ATPase and PM H+-ATPase dictates the distribution of OAs into either the vacuolar lumen or the apoplastic space that, in turn, determines Al tolerance capacity in plants.