College of Horticulture, Nanjing Agricultural University, Nanjing 210095, P. R. China.
Botanical Gardens, Tohoku University, Aoba, Sendai 980-0862, Japan.
Sci Rep. 2017 Jan 4;7:39915. doi: 10.1038/srep39915.
Manganese (Mn) is an important micronutrient element required for plant growth and development, playing catalytic roles in enzymes, membranes and DNA replication. The tea plant (Camellia sinensis) is able to accumulate high concentration of Mn without showing signs of toxicity, but the molecular mechanisms underlying this remain largely unknown. In this study, the C. sinensis cultivar 'LJCY' had higher Mn tolerance than cultivar 'YS', because chlorophyll content reduction was lower under the high Mn treatment. Proteomic analysis of the leaves revealed that C. sinensis Metal Tolerance Protein 8 (CsMTP8) accumulated in response to Mn toxicity in cultivar 'LJCY'. The gene encoding CsMTP8, designated as CsMTP8 was also isolated, and its expression enhanced Mn tolerance in Saccharomyces cerevisiae. Similarly, the overexpression of CsMTP8 in Arabidopsis thaliana increased plant tolerance and reduced Mn accumulation in plant tissues under excess Mn conditions. Subcellular localization analysis of green florescence fused protein indicated that CsMTP8 was localized to the plasma membranes. Taken together, the results suggest that CsMTP8 is a Mn-specific transporter, which is localized in the plasma membrane, and transports excess Mn out of plant cells. The results also suggest that it is needed for Mn tolerance in shoots.
锰（Mn）是植物生长和发育所必需的重要微量元素，在酶、膜和 DNA 复制中发挥催化作用。茶树（Camellia sinensis）能够积累高浓度的锰而没有表现出毒性的迹象，但这背后的分子机制在很大程度上仍然未知。在这项研究中，与品种 'YS' 相比，茶树品种 'LJCY' 具有更高的锰耐受性，因为在高锰处理下叶绿素含量的减少较低。叶片的蛋白质组学分析表明，茶树金属耐受蛋白 8（CsMTP8）在品种 'LJCY' 中对锰毒性作出响应而积累。编码 CsMTP8 的基因，被指定为 CsMTP8，也被分离出来，并且其在酿酒酵母中的表达增强了对锰的耐受性。同样，在拟南芥中过表达 CsMTP8 可提高植物在过量锰条件下的耐受性并减少植物组织中的锰积累。绿色荧光融合蛋白的亚细胞定位分析表明，CsMTP8 定位于质膜。综上所述，这些结果表明 CsMTP8 是一种锰特异性转运蛋白，它定位于质膜，将过量的锰运出植物细胞。这些结果还表明，它是 shoot 中锰耐受性所必需的。
