Tonoplast-localized transporter ZmNRAMP2 confers root-to-shoot translocation of manganese in maize
Tonoplast-localized transporter ZmNRAMP2 confers root-to-shoot translocation of manganese in maize
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DOI：
10.1093/plphys/kiac434
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发表时间：
2022-09-16
期刊：
影响因子：
7.4
通讯作者：
Yuan, Lixing
中科院分区：
文献类型：
--
作者：
Guo, Jingxuan;Long, Lizhi;Yuan, Lixing
几乎所有的生物都需要锰作为生存所必需的微量元素。为了在光合作用的放氧复合体中保持不可替代的作用，植物需要在根中有效地吸收锰并将其输送到地上组织。然而，根到冠的锰运输的潜在机制仍然不清楚。在此，我们在玉米(Zea Mays)中发现了一个天然抗性相关巨噬细胞蛋白(NRAMP)家族成员ZmNRAMP2，它定位于玉米原生质体的液泡膜上，并在酵母(Saccharmyces Cerevisiae)中介导了锰的运输。在缺锰条件下，两个缺失ZmNRAMP2基因的玉米突变体与相应的野生型(WT)植株相比，根-冠之间的锰转运显著减少，地上部的锰含量降低，F-v/F-m显著降低，植株生长受到抑制。ZmNRAMP2转录本在根中柱的木质部薄壁细胞中高表达。与野生型相比，突变体zmnramp2-1木质部汁液中的锰含量较低，根中柱中的锰含量较低。此外，ZmNRAMP2基因在转基因玉米中的过表达增强了锰在根冠之间的运转，提高了玉米对缺锰的耐受性。综上所述，我们的研究揭示了ZmNRAMP2通过促进木质部薄壁细胞中液泡锰的释放来促进玉米植株对低锰胁迫的适应，从而在根到地上部的转运中发挥重要作用，并为培育耐低锰作物品种提供了一个有前景的转基因途径。液泡膜定位的转运蛋白通过介导根星状细胞的液泡锰释放来实现根到地上部的锰运输，从而促进玉米对低锰的耐性。
Almost all living organisms require manganese (Mn) as an essential trace element for survival. To maintain an irreplaceable role in the oxygen-evolving complex of photosynthesis, plants require efficient Mn uptake in roots and delivery to above-ground tissues. However, the underlying mechanisms of root-to-shoot Mn translocation remain unclear. Here, we identified an Natural Resistance Associated Macrophage Protein (NRAMP) family member in maize (Zea mays), ZmNRAMP2, which localized to the tonoplast in maize protoplasts and mediated transport of Mn in yeast (Saccharomyces cerevisiae). Under Mn deficiency, two maize mutants defective in ZmNRAMP2 exhibited remarkable reduction of root-to-shoot Mn translocation along with lower shoot Mn contents, resulting in substantial decreases in F-v/F-m and plant growth inhibition compared to their corresponding wild-type (WT) plants. ZmNRAMP2 transcripts were highly expressed in xylem parenchyma cells of the root stele. Compared to the WT, the zmnramp2-1 mutant displayed lower Mn concentration in xylem sap accompanied with retention of Mn in root stele. Furthermore, the overexpression of ZmNRAMP2 in transgenic maize showed enhanced root-to-shoot translocation of Mn and improved tolerance to Mn deficiency. Taken together, our study reveals a crucial role of ZmNRAMP2 in root-to-shoot translocation of Mn via accelerating vacuolar Mn release in xylem parenchyma cells for adaption of maize plants to low Mn stress and provides a promising transgenic approach to develop low Mn-tolerant crop cultivars.A tonoplast-localized transporter enables root-to-shoot manganese translocation via mediating vacuolar manganese release of root stellar cells and contributes to low manganese tolerance in maize.