Heavy metal ATPase 3 (HMA3) confers cadmium hypertolerance on the cadmium/zinc hyperaccumulator Sedum plumbizincicola
Heavy metal ATPase 3 (HMA3) confers cadmium hypertolerance on the cadmium/zinc hyperaccumulator Sedum plumbizincicola
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DOI：
10.1111/nph.14622
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发表时间：
2017-07-01
期刊：
影响因子：
9.4
通讯作者：
Xu, Wenzhong
中科院分区：
文献类型：
--
作者：
Liu, Huan;Zhao, Haixia;Xu, Wenzhong
镉(Cd)对大多数生物具有高度毒性，但一些稀有植物可在地上组织中超量积累Cd而不受毒性影响。超积累植物对Cd的解毒机制很有趣，但目前还不清楚。本研究从Cd/Zn超积累植物白花景天中分离到了与Cd解毒相关的重金属ATPase 3(SpHMA3)基因。为了研究SpHMA3在白花链霉菌和非超积累生态型景天中的生理功能，通过RNA干扰(RNAi)诱导SpHMA3的沉默和过表达，发现SpHMA3在酿酒酵母中的异源表达具有CD特异性转运活性。SpHMA3在枝条中高表达，定位于液泡膜。SpHMA3-RNAi系对Cd敏感，但对锌不敏感，Cd严重抑制新梢和幼叶的生长。在非超积累生态型白花蛇舌草中过表达SpHMA3可显著提高其对Cd的耐性和积累，但不能显著提高其对Cd的积累。这些结果表明，定位于液泡膜的SpHMA3在地上部对Cd的高表达在Cd解毒中起重要作用，有助于维持Cd污染土壤中白花蛇舌草幼叶的正常生长。
Cadmium (Cd) is highly toxic to most organisms, but some rare plant species can hyperaccumulate Cd in aboveground tissues without suffering from toxicity. The mechanism underlying Cd detoxification by hyperaccumulators is interesting but unclear.Here, the heavy metal ATPase 3 (SpHMA3) gene responsible for Cd detoxification was isolated from the Cd/zinc (Zn) hyperaccumulator Sedum plumbizincicola. RNA interference (RNAi)-mediated silencing and overexpression of SpHMA3 were induced to investigate its physiological functions in S. plumbizincicola and a nonhyperaccumulating ecotype of Sedum alfredii.Heterologous expression of SpHMA3 in Saccharomyces cerevisiae showed Cd-specific transport activity. SpHMA3 was highly expressed in the shoots and the protein was localized to the tonoplast. The SpHMA3-RNAi lines were hypersensitive to Cd but not to Zn, with the growth of shoots and young leaves being severely inhibited by Cd. Overexpressing SpHMA3 in the nonhyperaccumulating ecotype of S. alfredii greatly increased its tolerance to and accumulation of Cd, but not Zn.These results indicate that elevated expression of the tonoplast-localized SpHMA3 in the shoots plays an essential role in Cd detoxification, which contributes to the maintenance of the normal growth of young leaves of S. plumbizincicola in Cd-contaminated soils.