Regulatory roles of cytokinins and cytokinin signaling in response to potassium deficiency in Arabidopsis.
Regulatory roles of cytokinins and cytokinin signaling in response to potassium deficiency in Arabidopsis.
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DOI：
10.1371/journal.pone.0047797
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Shin R
中科院分区：
文献类型：
--
作者：
Nam YJ;Tran LS;Kojima M;Sakakibara H;Nishiyama R;Shin R
钾(K)是一种重要的植物宏量营养素，在植物整个生命周期中发挥着多种作用。已知细胞分裂素（ck）通过控制硝酸盐、磷酸盐和硫酸盐转运体的表达来调节常量营养素的稳态。尽管一些研究已经描述了一些常量营养素的ck信号缺乏，但对ck在K信号传导中的作用知之甚少。在缺钾条件下，CK含量下降。具体来说，ck缺陷突变体比野生型更能耐受低钾；而CK过积累的植株对低钾更为敏感，说明缺钾改变了CK代谢，导致CK含量降低。为了进一步研究这一现象，利用分子、遗传和生化方法分析了几种拟南芥系，包括CK缺陷突变体和CK受体突变体在低钾条件下的表现。低钾条件下，活性氧积累和根毛生长也受ck的影响。CK受体突变体失去了对缺钾信号的响应性，包括ROS积累和根毛生长，但缺钾突变体积累了更多的ROS，并表现出HAK5的上调表达，HAK5是一种高亲和力的钾吸收转运基因，在低钾胁迫下以ROS和乙烯依赖的方式迅速诱导，以响应低钾。我们得出结论，CK水平的降低可以快速有效地刺激低钾诱导的ROS积累、根毛生长和HAK5表达，从而使植物适应低钾条件。
Potassium (K) is an important plant macronutrient that has various functions throughout the whole plant over its entire life span. Cytokinins (CKs) are known to regulate macronutrient homeostasis by controlling the expression of nitrate, phosphate and sulfate transporters. Although several studies have described how CKs signal deficiencies for some macronutrients, the roles of CKs in K signaling are poorly understood. CK content has been shown to decrease under K-starved conditions. Specifically, a CK-deficient mutant was more tolerant to low K than wild-type; however, a plant with an overaccumulation of CKs was more sensitive to low K. These results suggest that K deprivation alters CK metabolism, leading to a decrease in CK content. To investigate this phenomenon further, several Arabidopsis lines, including a CK-deficient mutant and CK receptor mutants, were analyzed in low K conditions using molecular, genetic and biochemical approaches. ROS accumulation and root hair growth in low K were also influenced by CKs. CK receptor mutants lost the responsiveness to K-deficient signaling, including ROS accumulation and root hair growth, but the CK-deficient mutant accumulated more ROS and exhibited up-regulated expression of HAK5, which is a high-affinity K uptake transporter gene that is rapidly induced by low K stress in ROS- and ethylene-dependent manner in response to low K. From these results, we conclude that a reduction in CK levels subsequently allows fast and effective stimulation of low K-induced ROS accumulation, root hair growth and HAK5 expression, leading to plant adaptation to low K conditions.
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