Gong Xiaoqing, Zhang Jingyan, Hu Jianbing, Wang Wei, Wu Hao, Zhang Qinghua, Liu Ji-Hong
Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan, 430070, China.
Plant Cell Environ. 2015 Nov;38(11):2248-62. doi: 10.1111/pce.12539. Epub 2015 Apr 27.
WRKY comprises a large family of transcription factors in plants, but most WRKY members are still poorly understood. In this study, we report functional characterization of a Group III WRKY gene (FcWRKY70) from Fortunella crassifolia. FcWRKY70 was greatly induced by drought and abscisic acid, but slightly or negligibly by salt and cold. Overexpression of FcWRKY70 in tobacco (Nicotiana nudicaulis) and lemon (Citrus lemon) conferred enhanced tolerance to dehydration and drought stresses. Transgenic tobacco and lemon exhibited higher expression levels of ADC (arginine decarboxylase), and accumulated larger amount of putrescine in comparison with wild type (WT). Treatment with D-arginine, an inhibitor of ADC, caused transgenic tobacco plants more sensitive to dehydration. Knock-down of FcWRKY70 in kumquat down-regulated ADC abundance and decreased putrescine level, accompanied by compromised dehydration tolerance. The promoter region of FcADC contained two W-box elements, which were shown to be interacted with FcWRKY70. Taken together, our data demonstrated that FcWRKY70 functions in drought tolerance by, at least partly, promoting production of putrescine via regulating ADC expression.
WRKY在植物中构成了一个庞大的转录因子家族，但大多数WRKY成员仍未被充分了解。在本研究中，我们报道了来自粗皮枳壳的一个III类WRKY基因（FcWRKY70）的功能特性。FcWRKY70受干旱和脱落酸强烈诱导，但受盐和冷胁迫诱导轻微或可忽略不计。FcWRKY70在烟草（裸烟草）和柠檬（尤力克柠檬）中过表达赋予了对脱水和干旱胁迫更强的耐受性。与野生型（WT）相比，转基因烟草和柠檬表现出更高水平的精氨酸脱羧酶（ADC）表达，并且积累了更多的腐胺。用ADC抑制剂D-精氨酸处理使转基因烟草植株对脱水更敏感。在金橘中敲低FcWRKY70下调了ADC丰度并降低了腐胺水平，同时脱水耐受性受损。FcADC的启动子区域包含两个W-盒元件，已证明它们与FcWRKY70相互作用。综上所述，我们的数据表明FcWRKY70至少部分地通过调节ADC表达促进腐胺的产生来发挥耐旱功能。
