Cloning And Functional Analyses Of Dehydration Induced Transcription Factor Gene MfWRKY41 In Resurrection Plant Myrothamnus Flabellifolia Xiaojuan Zhong

Myrothamnus flabellifolia is the only woody resurrection plant found to date.Previous transcriptome analysis revealed that a large number transcription factor were induced in dehydration.In the present study,one of the dehydration-induced WRKY transcription factor,MfWRKY41,was isolated and characterized,and transformed into model plant Arabidopsis thaliana.Several positive transgenic lines are phenotyped under stress treatment.The main results obtained are as following:1.Cloning and sequence analysis of the MfWRKY41 geneBased on the MfWRKY41 uniGene sequence,full length cDNA of 950bp was obtained.The deduced amino acids sequence showed that MfWRKY41 contains a highly conserved nuclear localization signal sequence KKRK,a typical WRKY domain of 63 amino acid residues and a Cx7Cx23HxC zinc finger structure,which determines it to the Group ? of WRKY family.2.Generation and morphological differences of transgenic linesAn eukaryotic expression vector was constructed to over-expression MJWRKY41 into Arabidopsis.Several positive and homozygous transgenic lines were harvested by Agrobacterium-mediated transformation method.In addition to the Line A,no significant morphological difference was found between wild type(WT)and all transgenic lines.Line A represents more weak than WT and the other transgenic lines.The average root length of Line A were significantly lower than those of WT and other lines.3.Tolerance of transgenic seedlings to abiotic stressesThe transgenic lines were treated by different concentrations of NaCl and mannitol.The results show that under 3 00mmol/L mannitol stress,the transgenic plants seedlings showed no significant tolerance to mannitol stress.Under the 150 mmol/L NaCl stress,the survival rate of Line K is slightly higher than other lines and WT,and its average root length was significantly higher.At 250 mmol/L NaCl conditions,with enhanced NaCl stress,all the plants after germination cannot grow normally.At different concentrations of NaCl stress,the germination rate of Line A is significantly lower than WT and other lines,indicating that Line A is more sensitive to salt stress than other lines.4.The tolerance of adult transgenic lines to NaCl stressUnder 300mmol/L NaCl treatment,Line K exhibits the best tolerance to NaCl.Under NaCl stress,the WT plants quickly wilted and turned to yellow,most of the plants cannot survive even after rehydration.However,the Line K have the lightest symptoms under stress comparing to other lines.Seven days after rehydration,the plants recovered to normal growth status.The survival rate of Line K was significantly higher than WT.