钾素对马铃薯钾转运体KUP6和KUP7基因表达量的调节

为了研究不同钾素浓度对钾转运体KUP6和KUP7基因表达量的影响,通过水培法培养马铃薯幼苗,通过提取马铃薯总RNA,经检测合格后用反转录试剂盒合成其c DNA的第一链。运用实时荧光定量核酸扩增检测技术对幼苗叶片进行基因转录水平的检测。在马铃薯幼苗种植后的第10,20,30天分别测定马铃薯幼苗根、茎和叶中钾的含量,并进行统计分析。结果表明:钾素浓度为1.00 mmol/L时,KUP6和KUP7基因表达量最高,且与其他处理有显著差异;钾素浓度低于0.10 mmol/L时,表达量较低,钾素浓度为10.00 mmol/L时该基因表达量也降低。表明较高和较低的钾离子浓度都不利于KUP6和KUP7基因的表达。通过对根、茎和叶内钾素含量测定表明:对于根系来说,钾素浓度在1.0 mmol/L时已到达其吸收饱和值;在钾素浓度为1.00,10.00 mmol/L的高钾水培中,马铃薯根、茎和叶钾素含量大于水培钾素浓度为0.01,0.10 mmol/L的低钾处理;在低钾水培条件下,茎叶随着培养时间的延长,其钾素含量之间的差异逐渐减小,而在高钾条件下,其差异逐渐增大。

Potassium Transporter KUP7 Is Involved in K^＋ Acquisition and Translocation in Arabidopsis Root under K^＋-Limited Conditions

Potassium （K^＋） is one of the essential macronutrients for plant growth and development. K^＋ uptake from environment and K^＋ translocation in plants are conducted by K^＋ channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K^＋ uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on Iow-K^＋ medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K^＋ uptake rate and K^＋ content in xylem sap under W-deficient conditions. Thus, the K^＋ content in kup7 shoot was significantly reduced under Iow-K^＋ conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K^＋ transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level inArabidopsis root. Together, our data demonstrated that KUP7 is crucial for K^＋ uptake inArabidopsis root and might be also involved in K^＋ transport into xylem sap, affecting K^＋ translocation from root toward shoot, especially under K^＋-Iimited conditions.