Expression Analysis Of Arabidopsis WRKY6 And PR1 In Responses To Biotic And Abiotic Stress

As sessile organisms,plants must cope with all kinds of environmental pressures in the whole life.As environmental perturbations may occur repeatedly,plant evolved their own"memory" mechanisms to adapt to new challenges.Defense priming as a mechanism to induce systemic resistance in plants mainly occurs at the transcriptional level.In the primed state,response of the gene transcription to biotic and abiotic shows faster,stronger and more sensitive pattern.At the same time plants have evolved the systemic acquired resistance mechanism which is an active defense mechanism of plants to avoid the extreme damage.A series signal transductions are needed from the stress signal and stress response occurrence to resistance emergence of plants.WRKY transcription factor and PATHOGENESIS RELATED proteins play an important role in the plant defense.The WRKY6 and PR1(PATHOGENESIS RELATED 1)are well-known stress response genes in Arabidopsis thaliana both encoding transcription factors.In this study we mainly focused on the expression patterns of WRKY6 and PR1 to various biotic/abiotic stresses.The main research work and results are as follows:1 Obtained the gene transcriptome data of WRKY6 and PR1 from Arabidopsis thaliana eFP database,analysis then made the expression heat map of WRKY6 and PR1 under the abiotic stress and biotic stress.WRKY6 and PR1 have similar,but also different expression patterns under various stress treatment.2 Established the systemic acquired resistance in Arabidopsis thaliana induced by Pseudomonas syringae pv.tomato(Pst)DC3000.Real-time qRT-PCR showed that although WRKY6 and PR1 responded to Pseudomonas syringae pv.tomato(Pst)DC3000 treatment at different time course the mRNA levels of WRKY6 and PR1 showed a certain increased trend.3 Treatment by BTH,the analogue of plant hormones SA,can induce slightly WRKY6 expression,while can significantly induce PR1 expression.To test the stress memory,the combination of BTH and mechanical stress could induce the transcriptional memory of WRKY6,but not PR1,suggesting that WRKY6 and PR1 may have different regulatory mechanism during stress treatment.Exogenous application JA can induce the differential expression of Thi2.1;:GUS in root hypocotyl and other parts of Arabidopsis thaliana.4 The homozygous T-DNA insertion mutants of Plant defense genes PDF1.2(Plant defensin 1.2)were obtained by genotyping in order to further study the cross talk between jasmonic acid signaling and salicylic acid signaling during defense response.5 Under the various abiotic stress semi-quantitative RT-PCR showed that WRKY6 and PR1 expression might have independent patterns in the root and shoot(aerial part)tissues.6 At last,an overexpression plasmid of 35S::WRKY6-GR was constructed by the Greengate cloning method,it could provide us foundation for further study on the regulation of downstream target genes and signaling pathway by WRKY6.In summary,the expression patterns of WRKY6 and PR1 after various stress and plant hormones treatments,indicate that WRKY6 and PR1 react differently after diverse treatments indicating that both genes act widely independent of each other.Also,the regulatory function of the plant stress response were complexity and diversity.This study provides theoretical and practical bases for further exploration of plant defense priming and stress memory mechanisms.