Wang Junjuan, Tao Fei, Tian Wei, Guo Zhongfeng, Chen Xianming, Xu Xiangming, Shang Hongsheng, Hu Xiaoping
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
Agricultural Research Service, Department of Agriculture and Department of Plant Pathology, Washington State University, Pullman, Washington, United States of America.
PLoS One. 2017 Jul 25;12(7):e0181963. doi: 10.1371/journal.pone.0181963. eCollection 2017.
WRKY transcription factors (TFs) play crucial roles in plant resistance responses to pathogens. Wheat stripe rust, caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is a destructive disease of wheat (Triticum aestivum) worldwide. In this study, the two WRKY genes TaWRKY49 and TaWRKY62 were originally identified in association with high-temperature seedling-plant resistance to Pst (HTSP) resistance in wheat cultivar Xiaoyan 6 by RNA-seq. Interestingly, the expression levels of TaWRKY49 and TaWRKY62 were down- and up-regulated, respectively, during HTSP resistance in response to Pst. Silencing of TaWRKY49 enhanced whereas silencing TaWRKY62 reduced HTSP resistance. The enhanced resistance observed on leaves following the silencing of TaWRKY49 was coupled with increased expression of salicylic acid (SA)- and jasmonic acid (JA)-responsive genes TaPR1.1 and TaAOS, as well as reactive oxygen species (ROS)-associated genes TaCAT and TaPOD; whereas the ethylene (ET)-responsive gene TaPIE1 was suppressed. The decreased resistance observed on leaves following TaWRKY62 silencing was associated with increased expression of TaPR1.1 and TaPOD, and suppression of TaAOS and TaPIE1. Furthermore, SA, ET, MeJA (methyl jasmonate), hydrogen peroxide (H2O2) and abscisic acid (ABA) treatments increased TaWRKY62 expression. On the other hand, MeJA did not affect the expression of TaWRKY49, and H2O2 reduced TaWRKY49 expression. In conclusion, TaWRKY49 negatively regulates while TaWRKY62 positively regulates wheat HTSP resistance to Pst by differential regulation of SA-, JA-, ET and ROS-mediated signaling.
WRKY转录因子在植物对病原体的抗性反应中发挥着关键作用。由真菌病原体条锈菌（Puccinia striiformis f. sp. tritici，Pst）引起的小麦条锈病是全球小麦（Triticum aestivum）的一种毁灭性病害。在本研究中，通过RNA测序最初在小麦品种小偃6中鉴定出两个WRKY基因TaWRKY49和TaWRKY62，它们与对条锈菌的高温成株抗性（HTSP）相关。有趣的是，在对条锈菌的HTSP抗性过程中，TaWRKY49和TaWRKY62的表达水平分别下调和上调。沉默TaWRKY49增强了HTSP抗性，而沉默TaWRKY62则降低了HTSP抗性。在沉默TaWRKY49后，叶片上观察到的抗性增强与水杨酸（SA）和茉莉酸（JA）响应基因TaPR1.1和TaAOS以及活性氧（ROS）相关基因TaCAT和TaPOD的表达增加有关；而乙烯（ET）响应基因TaPIE1受到抑制。在沉默TaWRKY62后，叶片上观察到的抗性降低与TaPR1.1和TaPOD的表达增加以及TaAOS和TaPIE1的抑制有关。此外，SA、ET、茉莉酸甲酯（MeJA）、过氧化氢（H2O2）和脱落酸（ABA）处理增加了TaWRKY62的表达。另一方面，MeJA不影响TaWRKY49的表达，而H2O2降低了TaWRKY49的表达。总之，TaWRKY49通过对SA、JA、ET和ROS介导的信号进行差异调节，对小麦对条锈菌的HTSP抗性起负调控作用，而TaWRKY62起正调控作用。
