Transcription Factor Atmyb13Inhibits Arabidopsis Resistance To A Bacterial Pathogen

Transcription factors are important regulators in the gene expression that interact with cis-elements in the promoter of downstream genes and are a critical part of plant growth and response to stresses. The MYB family has the largest number of transcription factors that contains at least one MYB domain in Arabidopsis gene family. Recent researches show the important role of MYB transcription factors in the regulation of secondary metabolism, response to hormones and environmental stresses, and also involved in the control of cell differentiation and morphogenesis. Some members of the MYB transcription factors have been clearly explained, however, not each is well characterized. Here we studied the expression pattern of AtMYB13, one of the MYB members, after treatment with hormones and pathogen infection, and the localization of AtMYB13protein in plant, in order to explain the role of AtMYB13in plant defense against Pseudomonas syringae in Arabidopsis.1. AtMYB13transcription factor inhibits plant defense againstPseudomonas syringae in ArabidopsisA common feature of plant defense responses is the transcriptional regulation of a large number of genes upon treatment with hormone or pathogen infection. Recent researches suggest that plant MYB transcription factors are involved in plant defense including transcriptional regulation of plant host genes in response to pathogen infection. Researches show that when plants were stimulated from the bad condition such as wound, pathogen and worms, callose formed and deposited in sieve tube which is related to plant defense.Here we analyzed the role of the MYB transcription factor from Arabidopsis in plant defense against the bacterial pathogen Pseudomonas syringae. Expression of AtMYB13is responsive to general hormones such as SA and JA. Here we analyzed the expression pattern of AtMYB13after Pst DC3000treatment in the defense signaling mutants abil-1, jar1-1, ein2-1and npr1-1. T-DNA insertion mutants for mybl3reduced growth of Pseudomonas syringae, increased callose deposition and cell death, displayed reduced disease symptom severity as compared to wild-type plants. The myb13mutant plants also displayed increased expression of the SA-regulated PR1gene after the pathogen infection. Based on analysis of T-DNA insertion mutants, transcription factor AtMYB13functions as an inhibitor of defense responses to Pseudomonas syringae in Arabidopsis.2. Prokaryotic expression and subcellular localization of the AtMYB13transcription factorTranscription factor binds and interacts with the promoter region of downstream gene specific to regulate its expression at transcription level in the nucleus. It is important to get the transcription factor protein to study the interaction with DNA in vitro.In the study, AtMYB13gene was amplified by PCR from wild type Arabidopsis thaliana Col-0. Purified AtMYB13fragment was ligased to pET30a(+) vector, creating recombinant plasmid pET30a(+)-AtMYB13, which fused to a His-tag-encoding sequence. Recombinant AtMYB13protein was produced and subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), which revealed the protein together with His-tag as30kDa in size. Western blot show that we have got the purified protein. Cloned into pBI121-GFP vector, we got the eukaryotic expression and transformation plasmid pBI121-AtMYB13-GFP. Resulting unit was transferred into onion epidermal cells using EHA105. Fluorescent detection has confirmed that AtMYB13transcription factor was localized in the nucleus.