A Newly Identified Passive Hyperaccumulator Eucalyptus grandis × E. urophylla under Manganese Stress.
A Newly Identified Passive Hyperaccumulator Eucalyptus grandis × E. urophylla under Manganese Stress.
复制标题
锰胁迫下新鉴定的被动超积累植物巨桉 x 尾叶桉
DOI：
10.1371/journal.pone.0136606
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Wang Q
中科院分区：
文献类型：
--
作者：
Xie Q;Li Z;Yang L;Lv J;Jobe TO;Wang Q
锰是植物生长发育所必需的微量营养素，但过量会对植物产生毒害作用。然而，一些植物物种具有解毒机制，允许它们积累锰到通常有毒的水平，这一现象被称为过度积累。这些物种是开发成本效益高的锰污染土壤修复策略的极佳候选者。本研究于2010年7月在中国南部进行野外调查，发现了一种新的被动超积累植物巨桉×尾叶桉。该杂交种可在叶片中积累高达13,549 mg/kg的干重锰。扫描电子显微镜(SEM)X射线显微分析结果表明，锰分布于整个叶片和茎的横截面，尤其是光合栅栏、海绵状叶肉组织和茎木质部维管束。尺寸排斥层析与电感耦合等离子体质谱联用的结果使我们推测，为了避免锰的毒性，锰与相对高相对分子质量的蛋白质和包括酒石酸在内的低分子有机酸结合在一起。我们的结果为蛋白质和有机酸在巨尾桉锰脱毒中起重要作用提供了实验证据。巨尾桉的主要特征是通过木质部的蒸腾作用促进锰的转运，进而促进锰在叶片组织中的分布。此外，首次获得了巨尾桉不同细胞器中锰的形态分布，表明不同细胞器具有不同的积累能力和独特的锰解毒机制。
Manganese (Mn) is an essential micronutrient needed for plant growth and development, but can be toxic to plants in excess amounts. However, some plant species have detoxification mechanisms that allow them to accumulate Mn to levels that are normally toxic, a phenomenon known as hyperaccumulation. These species are excellent candidates for developing a cost-effective remediation strategy for Mn-polluted soils. In this study, we identified a new passive Mn-hyperaccumulator Eucalyptus grandis × E. urophylla during a field survey in southern China in July 2010. This hybrid can accumulate as much as 13,549 mg/kg DW Mn in its leaves. Our results from Scanning Electron Microscope (SEM) X-ray microanalysis indicate that Mn is distributed in the entire leaf and stem cross-section, especially in photosynthetic palisade, spongy mesophyll tissue, and stem xylem vessels. Results from size-exclusion chromatography coupled with ICP-MS (Inductively coupled plasma mass spectrometry) lead us to speculate that Mn associates with relatively high molecular weight proteins and low molecular weight organic acids, including tartaric acid, to avoid Mn toxicity. Our results provide experimental evidence that both proteins and organic acids play important roles in Mn detoxification in Eucalyptus grandis × E. urophylla. The key characteristics of Eucalyptus grandis × E. urophylla are an increased Mn translocation facilitated by transpiration through the xylem to the leaves and further distribution throughout the leaf tissues. Moreover, the Mn-speciation profile obtained for the first time in different cellular organelles of Eucalyptus grandis × E. urophylla suggested that different organelles have differential accumulating abilities and unique mechanisms for Mn-detoxification.