The Role Of Wrky Transcription Factors In The Elicitor-Triggered Hypersensitive Response And Stomatal Closure In Nicotiana Benthamiana

NbWRKY1 and NbWRKY2 are involved in the Group I WRKY proteins, which have two WRKYGQK motif and an atypical zinc-finger structure at the C-terminus.WRKY transcription factors function as the downstream in the MAPK (motigen-activated protein kinase) signal transduction pathway. WRKY transcription factors play pivotal roles in the regulation of plant defense, growth and development, substance metabolism. Here, we found that WRKY2 has been shown to physically interact with WIPK. And we describe the role of WRKY1 and WRKY2 from Nicotiana benthamiana via virus-induced gene silencing, in the response to three PAMPs:bacterial harpin, oomycete boehmerin and fungal Nepl. The HR was absent in WRKY1- and WRKY2-silenced plants treated with Nep1 alone. However, WRKY1- and WRKY2-silenced plants developed a normal HR after harpin and boehmerin treatment. These results suggest that Nepl-triggered HR is WRKY1 and WRKY2 dependent. In this report, we have provided evidence for a new signaling pathway controlling stomatal movement. We show that harpin, boehmerin and Nepl stimulates NbNOAl, NbNR, NbNR2-dependent production of NO, which acts as a second messenger to activate stomatal closure. Furthermore, we found that harpin, boehmerin and Nepl-triggered NO production is mediated by WRKY1 and WRKY2 in N. benthamiana. We also showed that the modulation of NO production by WRKY1 and WRKY2 requires NADPH oxidase-dependent hydrogen peroxide generation. And both factors play essential roles in the resistance of Phytophthora nicotianae and play a role in the defense cascade. QRT-PCR analyses showed that WRKY1 and WRKY2 are involved in the SA, JA and ET signal pathway.