Cloning And Funtional Characterization Of MfWRKY7 Gene In Myrothamnus Flabellifolia

Drought and salinization stress are the major abiotic hazards in plants today,and the growth and development of plants are seriously affected by them.Myrothamnus flabellifolia is also called South African Phoenix Grass,the only woody resuscitation plant in the world,which exhibits strong tolerance to dehydration environment.Therefore,it is important to study the response process of Myrothamnus flabellifolia to drought and salt stress,which can help to understand the stress response mechanism of plants and to improve the tolerance of plants to environmental stress.In this study,we isolated a WRKY transcription factor,named MfWRKY7 by homologous cloning from Myrothamnus flabellifolia,then we studied the stress resistance of Arabidopsis with overexpressed MfWRKY7 gene in morphology and physiology.The results laid a foundation for revealing the function and mechanism of MfWRKY7 gene in Myrothamnus flabellifolia.The main results obtained were list below:（1）Sequence analysis:MfWRKY7 gene was cloned from Myrothamnus flabellifolia.The sequence analysis showed:its core coding region was 987bp,encoding 328amino acids,with a predicted molecular weight of 36.062 k D,theoretical isoelectric point（p I）of 9.88,containing a conserved WRKYGQK core sequence and a Cx₅Cx₂₃Hx H zinc finger domain,belonging to the second category of WRKY transcription factor family.Phylogenetic tree analysis showed that MfWRKY7 was clustered into a single group,indicating that MfWRKY7 gene had high specificity,and there was little information about this kind of WRKY gene.（2）Phenotypic results:We transformed the MfWRKY7 gene into Arabidopsis and obtained the T₃generation positive transgenic plants with MfWRKY7 gene.In seedling treatment,wild-type and transgenic plants were treated with different concentrations of mannitol（200m M,250m M,300m M）and Na Cl（75m M,100m M,125m M）,and we observed that the transgenic plants’root length were significantly longer than wild type plants;In the adult-plant treatment,the growth and green rate of leaves of transgenic plants was better than that of wild-type plants in natural drought and 300m M Na Cl conditions.（3）The transgenic and wild-type plants were treated with drought and salt stress,and the leaf water loss rate,chlorophyll content,stomatal closure and proline content were determined.Compared with wild-type WT,the water loss rate of transgenic Arabidopsis was lower,the content of chlorophyll and proline was higher and stomatal closure was higher after stress treatment.The results showed that MfWRKY7 gene could respond to drought and high salt stress,and the overexpression enhanced the tolerance of plants to stress.In conclusion,the MfWRKY7-overexpressing plants showed good drought and salt stress tolerance.