The Roles Of Cucumber CsWRKY21 On Plant Drought Stress Responses

Cucumber is an edible horticultural crop of Cucurbitaceae,one of the most important horticultural crops cultivated in the world.In production practice,drought has a widespread impact on plants,and has a great impact on crop yields.At the same time,transcription factors can participate in plant response to stress and play an important role.This paper takes cucumber and transgenic over expressed Arabidopsis thaliana as research materials,to explore the expression pattern and function of CsWRKY21 in Cucumber under drought stress.By analyzing the changes of Cucumber Seedlings under drought stress,the expression changes of CsWRKY21 gene under drought and ABA,and the phenotype and function analysis of transgenic over expressed plants under drought stress,to explore the possible molecular regulation mechanism of this gene in Cucumber under drought stress,and to provide theoretical basis for solving the problems in horticultural crop production practice.The main conclusions are as follows:1.Effects of Drought Stress on Cucumber SeedlingsThis study shows that:when cucumber seedlings were under drought stress,the contents of chlorophyll a,B and total chlorophyll in plants decreased.At the same time,spraying ABA under these conditions can promote the increase of chlorophyll content,and then alleviate the effect of drought on plant chlorophyll synthesis.Spraying ABA pretreatment could alleviate the decrease of MDA content and increase the contents of soluble sugar,conductivity and antioxidant enzymes in Cucumber Seedlings under drought stress,which proved that ABA pretreatment had a positive effect on Drought Resistance of cucumber seedlings.2.cDNA Cloning and Bioinformatics Analysis of Cucumber CsWRKY21 This study shows that:The full-length reading frame sequence of CsWRKY21 was developed by RT-PCR cloning,the product was linked to pEASY-T1 vector,screened for blue and white spot,positive clones identified by colony PCR,expanded culture,plasmid extraction,double enzyme digestion and sequencing by Shanghai Biotechnology Company to obtain the gene's DNA sequence.According to subcellular localization of CsWRKY21 protein,measured out that 82.6%of the CsWRKY21 proteins were located in the nucleus and 13.0% in the cytoplasm.The results showed that CsWRKY21 was a transcription factor.3.Effects of Drought Stress on Physiological and Biochemical Indicators and Gene Expression of Transgenic Plants.This study showed that almost all wild type(WT)plants withered after drought stress,overexpression of transgenic plants(CsWRKY-OE2,CsWRKY-OE5)maintained a good state without being affected.The water content of wild type(WT)plants decreased significantly after drought stress,while the content of MDA,soluble sugar and proline increased,while the content of transgenic over expressed plants did not change significantly.qRT-PCR analysis showed that the over expression of DREB1 A,DREB2A,ABF4,ADH and other genes increased,therefore,it can be inferred that over expression of CsWRKY21 may regulate plant drought resistance pathway through ABA-dependent pathway.