Functional characterization of IlHMA2, a P1B2-ATPase in Iris lactea response to Cd
Functional characterization of IlHMA2, a P1B2-ATPase in Iris lactea response to Cd
复制标题
IlHMA2（一种 P1B2-ATP 酶）在鸢尾对 Cd 响应中的功能表征
DOI：
10.1016/j.envexpbot.2018.10.008
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发表时间：
2019-01-01
影响因子：
5.7
通讯作者：
Meng, Lin
中科院分区：
文献类型：
--
作者：
Guo, Qiang;Tian, Xiaoxia;Meng, Lin
重金属p - 1b2 - atp酶（HMAs）参与重金属的转运或解毒，维持植物体内的金属稳态。本文报道了单子叶鸢尾（Iris lactea）在Cd胁迫下HMAs的一个未知成员IlHMA2的功能。为了揭示IlHMA2在I. lactea对Cd反应中的作用，我们利用共聚焦成像技术确定了IlHMA2的亚细胞定位，并利用qRT-PCR技术研究了其在Cd或其他金属条件下的表达水平，然后通过rnai介导的基因沉默检测了植物生长、Zn和Cd的积累以及基因表达水平。IlHMA2主要在镉过量或锌缺乏的根中表达，蛋白定位于质膜。ilhma2沉默系对Cd敏感，并伴有严重的生长迟缓。进一步研究表明，与野生型相比，ilhma2沉默系木质部汁液中Cd和Zn的含量显著降低，Cd和Zn的根到梢转运显著减少。与此同时，与野生型相比，ilhma2沉默系不同组织中与Zn稳态相关的转运蛋白编码基因IlZIP2和IlMTP1的表达水平显著下调。这些结果表明，质膜转运蛋白IlHMA2通过调节锌转运系统，在锌和镉的根到茎转运和锌稳态维持中起关键作用，从而提高其耐镉性。
Heavy metal P-1B2-ATPases (HMAs) are involved in transport or detoxification of heavy metals to maintain metal homeostasis in plants. Here we report the function of an uncharacterized member of HMAs, IlHMA2, from the monocotyledon Iris lactea under Cd stress. To uncover the role of IlHMA2 in I. lactea response to Cd, subcellular localization of IlHMA2 was determined by confocal imaging and its expression levels were investigated under Cd or other metals conditions by qRT-PCR, and then plant growth, accumulation of Zn and Cd and genes expression level were measured by RNAi-mediated gene silencing. IlHMA2 was predominantly expressed in roots with either excess Cd or Zn deficiency, and the protein was localized to the plasma membrane. IlHMA2-silenced lines were hypersensitive to Cd with severe growth retardation. Further investigations showed that IlHMA2-silenced lines exhibited a dramatic reduction in Cd and Zn concentration in the xylem sap than wild type, which resulted in significantly decrease the root-to-shoot translocation of Cd and Zn. Meanwhile, the expression levels of genes encoding transporters related to Zn homeostasis, including IlZIP2 and IlMTP1, was significantly downregulated in different tissues of IlHMA2-silenced lines compared to wild type. These findings suggest that the plasma membrane transporter IlHMA2 plays a key role in root-to-shoot translocation of Zn and Cd and the maintenance of Zn homeostasis via modulating Zn transport systems, thereby improving its Cd tolerance.