桃钾转运体基因PpeKUP5的表达及功能分析

从‘霞晖8号’桃中克隆了一个定位于第4条染色体上的钾转运体基因PpeKUP5，该基因编码625个氨基酸，具有10个跨膜结构域；PpeKUP5主要在根部表达，其次是叶和茎中，花和果实中的表达量极低；ABA、重金属Cr和Zn处理均显著诱导其在桃幼苗各组织中的表达，其中Cr处理最为显著，高钾胁迫及重金属Cu处理显著降低了其在根部的表达水平；细菌互补试验表明PpeKUP5具有吸收外界K+（KCl或K2SO4）的功能，且在偏中性pH值条件下最为显著。本研究表明PpeKUP5是一个主导桃树根部K+吸收的钾转运体，并可能在桃树适应高钾及重金属Cr、Zn和Cu等胁迫处理和ABA 响应中起着重要作用。

Expression and Function Analysis of Potassium Transporter Gene PpeKUP5 in Peach

An K+ transporter encoding gene（PpeKUP5）was isolated from‘Xiahui 8’peach（Prunus persica）trees. The PpeKUP5 encodes a protein of 625 amino acid residues，which contains 10 transmembrane regions. The PpeKUP5 gene was largely expressed in roots，less in leaves and stems，and very weakly in flowers and fruits. Abscisic acid（ABA）treatment，heavy-metal chromium（Cr）and heavy-metal zinc（Zn），respectively，significantly enhanced the expression level of PpeKUP5 gene throughout whole peach seedlings. Notably，PpeKUP5 gene was most sensitive to Cr treatment. While both K+ excess and heavy-metal copper（Cu）treatment significantly reduced the expression level of PpeKUP5 gene in plant roots. Functional complementation of bacterial mutant showed that PpeKUP5 can utilize external K+（either KCl or K2SO4），especially under neutral pH values. This study favorably reveals that PpeKUP5 is a key K+ transporter mediates roots K+ uptake and accumulation in peach，which may play an important role in response to K+ excess，heavy-metal and ABA stresses.