Sequence Analysis And Expression Profiling Of WRKY Genes In Ramie

Ramie is one of the most important fiber crops in China. Since it has been gradually transplanted to the slope land, there have been more and more researches about drought resistance molecular mechanism. Transcription factors are key regulators in the response to environment of plant and studied widely in stress resistance. And the WRKY protein is a class of plant specific transcription factor, involved in various stress response pathways and growth regulation. However, at present, comparing with the model plant as Arabidopsis, rice and tobacco, other plants have not received much attention on the systematic research of WRKY gene family. In this study, we performed the gene cloning and expression analysis of ramie cultivar “Huazhu No.5”, basing on our previous three transcriptome database. The main results are as follows:(1) 26 genes were assembled from our previous three transcriptome database with complete CDS encoding WRKY proteins in ramie and separately cloned them from “Huazhu No.5”. They were designated as BnWRKY1 to BnWRKY26, respectively. Furthermore, the phylogenetic tree construction and intron- exon structure analysis were conducted for exploring the structural properties of WRKY gene family. And these selected genes each possessed the conserved WRKYGQK sequence and could be classified into three groups(group I, group II and group III).(2) By qRT-PCR analysis, all the 26 BnWRKYs were found differently expressed in leaves and roots at different development stages. In addition, these genes exhibited higher expression level at fiber maturation stage almost in all leaf samples. Moreover, all genes revealed differently degrees of response to NaCl or PEG treatment. In particular, the BnWRKY17 was found to have significant increase in root under NaCl treatment. Meanwhile, the AtWRKY40 of Arabidopsis, homologous to BnWRKY17 gene, had been detected to play a vital role in plant stress resistance, including high-salt stress, ethylene stress, fungi stress, etc. Therefore we supposed that BnWRKY17 would possess some similar regulatory functions in plant defense responses.These results will further enrich the foundation study of ramie WRKY family, and could provide potential gene resources for molecular breeding in ramie.