The potassium transporter AtHAK5 functions in K+ deprivation-induced high-affinity K+ uptake and AKT1 K+ channel contribution to K+ uptake kinetics in Arabidopsis roots
The potassium transporter AtHAK5 functions in K+ deprivation-induced high-affinity K+ uptake and AKT1 K+ channel contribution to K+ uptake kinetics in Arabidopsis roots
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DOI：
10.1104/pp.104.057216
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发表时间：
2005-03-01
期刊：
影响因子：
7.4
通讯作者：
Schroeder, JI
中科院分区：
文献类型：
--
作者：
Gierth, M;Mäser, P;Schroeder, JI
钾是一种重要的常量营养元素，也是植物体内含量最丰富的阳离子。由于土壤矿物质条件可能会有所不同，植物必须能够适应不同的养分供应。在这里，我们使用Affyssin基因芯片识别基因响应钾（K+）剥夺在成熟的拟南芥（拟南芥）植物的根。出乎意料的是，只有少数基因的表达水平改变后，6，48，96小时的K+饥饿，即使根K含量减少了约60%。AtHAK5是KUP/HAK/KT家族的钾转运蛋白基因，在48 h、96 h和7 d K+剥夺实验中其表达水平最一致和强烈上调。AtHAK 5启动子-β-葡萄糖醛酸苷酶和-绿色荧光蛋白融合显示AtHAK 5启动子活性的表皮和脉管系统的K剥夺根。Rb~+吸收动力学在athak5 T-DNA插入突变体和野生型植物的根证明了一个诱导的高亲和力Rb~+/K~+（K-m约15 - 24 μ m）运输系统的主要部分在athak5植物的情况下。在比较分析中，K+通道突变体akt1 - 1的吸收动力学表明，akt1 - 1根主要受损的主要运输机制，具有约0.9毫米K+（Rb+）的表观亲和力。数据显示适应的表观K+亲和力的拟南芥根时，个别K+转运蛋白基因被破坏。此外，有限的全转录组响应K+饥饿表明，转录后机制可能在根适应K+供应在拟南芥中发挥重要作用。结果表明AtHAK5在拟南芥根的诱导型高亲和力K+吸收系统中具有体内功能。
Potassium is an important macronutrient and the most abundant cation in plants. Because soil mineral conditions can vary, plants must be able to adjust to different nutrient availabilities. Here, we used Affymetrix Genechip microarrays to identify genes responsive to potassium (K+) deprivation in roots of mature Arabidopsis (Arabidopsis thaliana) plants. Unexpectedly, only a few genes were changed in their expression level after 6, 48, and 96 h of K+ starvation even though root K content was reduced by approximately 60%. AtHAK5, a potassium transporter gene from the KUP/HAK/KT family, was most consistently and strongly up-regulated in its expression level across 48-h, 96-h, and 7-d K+ deprivation experiments. AtHAK5 promoter-beta-glucuronidase and -green fluorescent protein fusions showed AtHAK5 promoter activity in the epidermis and vasculature of K deprived roots. Rb+ uptake kinetics in roots of athak5 T-DNA insertion mutants and wild-type plants demonstrated the absence of a major part of an inducible high-affinity Rb+/K+ (K-m approximately 15-24 mu m) transport system in athak5 plants. In comparative analyses, uptake kinetics of the K+ channel mutant akt1-1 showed that akt1-1 roots are mainly impaired in a major transport mechanism, with an apparent affinity of approximately 0.9 mm K+(Rb+). Data show adaptation of apparent K+ affinities of Arabidopsis roots when individual K+ transporter genes are disrupted. In addition, the limited transcriptome-wide response to K+ starvation indicates that posttranscriptional mechanisms may play important roles in root adaptation to K+ availability in Arabidopsis. The results demonstrate an in vivo function for AtHAK5 in the inducible high-affinity K+ uptake system in Arabidopsis roots.