Mingliang Jia

WRKY transcription factors (TFs), which are plant-specific TFs, play significant roles in plant defense. Here, a pathogen-induced WRKY gene, named AktWRKY12, which was the homologous gene of AtWRKY12, was isolated from Akebia trifoliata. The AktWRKY12 gene has a total length of 645 nucleotides and an open reading frame (ORF) encoding 214 amino acid polypeptides. The characterizations of AktWRKY12 were subsequently performed with the ExPASy online tool Compute pI/Mw, PSIPRED and SWISS-MODEL softwares. The AktWRKY12 could be classified as a member of WRKY group II-c TFs based on sequence alignment and phylogenetic analysis. The results of tissue-specific expression analysis revealed that the AktWRKY12 gene was expressed in all the tested tissues, and the highest expression level was detected in A. trifoliata leaves. Subcellular localization analysis showed that AktWRKY12 was a nuclear protein. Results showed that the expression level of AktWRKY12 significantly increased in A. trifoliata leaves with pathogen infection. Furthermore, heterologous over-expression of AktWRKY12 in tobacco resulted in suppressed expression of lignin synthesis key enzyme genes. Based on our results, we speculate that AktWRKY12 might play a negative role in A. trifoliata responding to biotic stress by regulating the expression of lignin synthesis key enzyme genes during pathogen infection.

GT factors play critical roles in plant growth and development and in response to various environmental stimuli. Considering the new functions of GT factors on the regulation of plant stress tolerance and seeing as few studies on Brachypodium distachyon were available, we identified GT genes in B. distachyon, and the gene characterizations and phylogenies were systematically analyzed. Thirty-one members of BdGT genes were distributed on all five chromosomes with different densities. All the BdGTs could be divided into five subfamilies, including GT-1, GT-2, GTγ, SH4, and SIP1, based upon their sequence homology. BdGTs exhibited considerably divergent structures among each subfamily according to gene structure and conserved functional domain analysis, but the members within the same subfamily were relatively structure-conserved. Synteny results indicated that a large number of syntenic relationship events existed between rice and B. distachyon. Expression profiles indicated that the expression levels of most of BdGT genes were changed under abiotic stresses and hormone treatments. Moreover, the co-expression network exhibited a complex regulatory network between BdGTs and BdWRKYs as well as that between BdGTs and BdMAPK cascade gene. Results showed that GT factors might play multiple functions in responding to multiple environmental stresses in B. distachyon and participate in both the positive and negative regulation of WRKY- or MAPK-mediated stress response processes. The genome-wide analysis of BdGTs and the co-regulation network under multiple stresses provide valuable information for the further investigation of the functions of BdGTs in response to environment stresses.