Li Min, Chen Huan, Chen Jian, Chang Ming, Palmer Ian A, Gassmann Walter, Liu Fengquan, Fu Zheng Qing
Department of Biological Sciences, University of South Carolina, Columbia, SC, United States.
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
Front Plant Sci. 2018 Aug 14;9:1153. doi: 10.3389/fpls.2018.01153. eCollection 2018.
In , TEOSINTE BRANCHED 1, CYCLOIDEA, PCF1 (TCP) transcription factors (TF) play critical functions in developmental processes. Recent studies suggest they also function in plant immunity, but whether they play an important role in systemic acquired resistance (SAR) is still unknown. NON-EXPRESSER OF PR GENES 1 (NPR1), as an essential transcriptional regulatory node in SAR, exerts its regulatory role in downstream genes expression through interaction with TFs. In this work, we provide biochemical and genetic evidence that TCP8, TCP14, and TCP15 are involved in the SAR signaling pathway. TCP8, TCP14, and TCP15 physically interacted with NPR1 in yeast two-hybrid assays, and these interactions were further confirmed . SAR against the infection of virulent strain pv. () ES4326 in the triple T-DNA insertion mutant was partially compromised compared with Columbia 0 (Col-0) wild type plants. The induction of SAR marker genes , and in local and systemic leaves was dramatically decreased in the mutant compared with that in Col-0 after local treatment with ES4326 carrying . Results from yeast one-hybrid and chromatin immunoprecipitation (ChIP) assays demonstrated that TCP15 can bind to a conserved TCP binding motif, GCGGGAC, within the promoter of , and this binding was enhanced by NPR1. Results from RT-qPCR assays showed that TCP15 promotes the expression of in response to salicylic acid induction. Taken together, these data reveal that TCP8, TCP14, and TCP15 physically interact with NPR1 and function redundantly to establish SAR, that TCP15 promotes the expression of through directly binding a TCP binding site within the promoter of , and that this binding is enhanced by NPR1.
在植物中，TEOSINTE BRANCHED 1、CYCLOIDEA、PCF1（TCP）转录因子在发育过程中发挥着关键作用。近期研究表明它们在植物免疫中也发挥作用，但它们是否在系统获得性抗性（SAR）中发挥重要作用仍不清楚。PR基因非表达子1（NPR1）作为SAR中一个重要的转录调控节点，通过与转录因子相互作用对下游基因表达发挥调控作用。在这项研究中，我们提供了生化和遗传学证据，证明TCP8、TCP14和TCP15参与了SAR信号通路。在酵母双杂交试验中，TCP8、TCP14和TCP15与NPR1发生了物理相互作用，并且这些相互作用得到了进一步证实。与哥伦比亚0（Col-0）野生型植物相比，三T-DNA插入突变体对强毒株丁香假单胞菌番茄致病变种（Pseudomonas syringae pv. tomato）（Pto）ES4326感染的SAR部分受损。在用携带avrPto的Pto ES4326进行局部处理后，与Col-0相比，突变体中局部和系统叶片中SAR标记基因PR1、PR2和PR5的诱导显著降低。酵母单杂交和染色质免疫沉淀（ChIP）试验结果表明，TCP15可以结合到PR1启动子内一个保守的TCP结合基序GCGGGAC上，并且这种结合被NPR1增强。RT-qPCR试验结果表明，TCP15响应水杨酸诱导促进PR1的表达。综上所述，这些数据表明TCP8、TCP14和TCP15与NPR1发生物理相互作用，并在建立SAR过程中发挥冗余功能；TCP15通过直接结合PR1启动子内的一个TCP结合位点促进PR1的表达，并且这种结合被NPR1增强。
