United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, Japan.
Plant Cell Physiol. 2018 Jul 1;59(7):1443-1451. doi: 10.1093/pcp/pcy074.
The involvement of the Arabidopsis oligopeptide transporter AtOPT6, which was previously shown to take up glutathione (GSH) when expressed in yeast cells or in Xenopus laevis oocytes, in GSH transport was analyzed using opt6 knockout mutant lines. The concentration of GSH in flowers or siliques was lower in opt6 mutants relative to wild-type plants, suggesting involvement of AtOPT6 in long-distance transport of GSH. The GSH concentration in phloem sap was similar between opt6 mutants and wild-type plants. These results, combined with earlier reports showing expression of AtOPT6 in the vascular bundle, especially in the cambial zone, suggest that AtOPT6 functions to transport GSH into cells surrounding the phloem in sink organs. The opt6 mutant plants showed delayed bolting, implying the importance of AtOPT6 for regulation of the transition from vegetative to reproductive growth. After cadmium (Cd) treatment, the concentration of the major phytochelatin PC2 was lower in flowers in the opt6 mutants and Cd was accumulated in roots of opt6 mutant plants compared with wild-type plants. These results suggest that AtOPT6 is likely to be involved in transporting GSH, PCs and Cd complexed with these thiols into sink organs.
先前的研究表明，拟南芥寡肽转运蛋白 AtOPT6 在酵母细胞或非洲爪蟾卵母细胞中表达时能摄取谷胱甘肽（GSH），本研究利用 opt6 敲除突变体系分析了其在 GSH 转运中的作用。与野生型植物相比，opt6 突变体花或蒴果中的 GSH 浓度较低，提示 AtOPT6 参与 GSH 的长距离运输。opt6 突变体和野生型植物的韧皮部汁液中 GSH 浓度相似。这些结果与之前的报告表明 AtOPT6 在维管束中表达，特别是在形成层区域，提示 AtOPT6 可将 GSH 转运到韧皮部周围的细胞中。opt6 突变体植物表现出出芽延迟，这暗示了 AtOPT6 对从营养生长向生殖生长的转变的调控具有重要作用。在镉（Cd）处理后，opt6 突变体花中的主要植物螯合肽 PC2 浓度较低，与野生型植物相比，Cd 积累在 opt6 突变体植物的根中。这些结果表明，AtOPT6 可能参与将 GSH、PCs 和与这些巯基结合的 Cd 转运到靶器官。
