Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, 570228, Hainan, People's Republic of China.
Plant Cell Rep. 2020 Aug;39(8):1095-1107. doi: 10.1007/s00299-020-02551-x. Epub 2020 May 12.
Overexpression of HbWRKY40 induces ROS burst in tobacco and increases disease resistance in Arabidopsis; RNA-seq and ChIP assays revealed the regulatory network of HbWRKY40 in plant defense. WRKY, a family of plant transcription factors, are involved in the regulation of numerous biological processes. In rubber tree Hevea brasiliensis, the roles of WRKYs remain poorly understood. In the present study, a total of 111 genes encoding putative HbWRKY proteins were identified in the H. brasiliensis genome. Among these genes, HbWRKY40 transcripts were significantly induced by Colletotrichum gloeosporioides and salicylic acid. To assess its roles in plant defense, HbWRKY40 was over-expressed in Nicotiana benthamiana and Arabidopsis thaliana. The results showed that HbWRKY40 significantly induced reactive oxygen species burst in N. benthamiana and increased resistance of Arabidopsis against Botrytis cinerea. Transient expression in mesophyll cell protoplasts of H. brasiliensis showed that HbWRKY40 localizes at nuclei. In addition, transcripts of 145 genes were significantly up-regulated and 6 genes were down-regulated in the protoplasts over-expressing HbWRKY40 based on the RNA-seq analysis. Among these potential downstream targets, 12 genes contain potential WRKY-binding sites at the promoter regions. Further analysis through chromatin immunoprecipitation revealed that 10 of these 12 genes were the downstream targets of HbWRKY40. Taken together, our findings indicate that HbWRKY40 plays an important role in the disease resistance by regulating defense-associated genes in H. brasiliensis.
HbWRKY40 的过表达会导致烟草中 ROS 的爆发，并增加拟南芥的抗病性；RNA-seq 和 ChIP 分析揭示了 HbWRKY40 在植物防御中的调控网络。WRKY 是一类植物转录因子，参与调控许多生物过程。在橡胶树 Hevea brasiliensis 中，WRKYs 的作用仍知之甚少。本研究在巴西橡胶树基因组中鉴定了 111 个编码假定 HbWRKY 蛋白的基因。在这些基因中，HbWRKY40 的转录物被胶孢炭疽菌和水杨酸显著诱导。为了评估其在植物防御中的作用，在烟草原生质体和拟南芥中过表达了 HbWRKY40。结果表明，HbWRKY40 显著诱导烟草原生质体中活性氧的爆发，并提高了拟南芥对灰葡萄孢的抗性。巴西橡胶树原生质体的瞬时表达表明 HbWRKY40 定位于细胞核。此外，基于 RNA-seq 分析，过表达 HbWRKY40 的原生质体中 145 个基因的转录物显著上调，6 个基因下调。在这些潜在的下游靶标中，启动子区域有 12 个基因含有潜在的 WRKY 结合位点。进一步的染色质免疫沉淀分析表明，这 12 个基因中的 10 个是 HbWRKY40 的下游靶标。综上所述，我们的研究结果表明，HbWRKY40 通过调控巴西橡胶树中与防御相关的基因，在抗病性中发挥重要作用。
