A Multi-omics Study Of Herbaspirillum Huttiense 5-28 Inducing Resistance To Pst DC3000 In Arabidopsis

Under the background of advocating sustainable ecological development,the use of chemical pesticides should be cut down to reduce environmental pollution.Among them,biological control has developed rapidly in recent years.It has become a research hotspot to use beneficial microorganisms to improve the stress resistance of plant and to alleviate and control plant diseases.In the past,studies on the ability of Herbaspirillumto induce plant resistance were relatively rare,although there have been many reports on it as a plant growth-promoting bacterium.H.5-28(Herbaspirillum huttiense 5-28)is a new strain of Herbaspirillum isolated and identified in our laboratory.It has also been found to promote growth of various plants such as wheat,maize,Isatis indigotica and others.Moreover,the disease of Arabidopsis thaliana leaves caused by Pst DC3000 has a certain alleviation effect,but the molecular mechanism of how to induce the disease resistance in Arabidopsis thaliana is still unclear.For the sake of making H.5-28 better applied in biological control,this paper will carry out research from the following two aspects:one is to study the alleviation effect of H.5-28 on the disease of Arabidopsis thaliana caused by Pst DC3000 by using epigenetic statistics;the other is to study the intrinsic mechanism of resistance of Arabidopsis thaliana to Pst DC3000 induced by H.5-28 through metabolomics and transcriptome.The main findinds are as follows:1.H.5-28 alleviates the detection of Arabidopsis thaliana disease by Pst DC3000.Pst DC3000 was inoculated after three days pretreatment with H.5-28,compared with the control group inoculated with Pst DC3000 but without H.5-28,the incidence of the disease decreased from 55.51%to 28.94%,The incidence rate decreased from 55.51%to 28.94%,the disease index decreased from 70.38%to 48.48%,and the disease control effect was 47.87%,indicating that H.5-28 has significant relief of Pst DC3000 on Arabidopsis thaliana disease effect.2.To explore the H.5-28-induced response Arabidopsis thaliana response to Psi DC3000 resistance at the metabolite level,we performed non-target metabolomics testing(GC-MS)on Arabidopsis thaliana leaves of black control,H.5-28 group,Pst DC3000 group,H.5-28 and Pst DC3000 co-group.The results showed that there were 23,102 and 107 different metabolites in H.5-28 group,Pst DC3000 group,H.5-28 and Pst DC3000 co-group,respectively,compared with the blank control.There were 95 different metabolites in H.5-28 and Pst DC3000 co-group compared with Psi DC3000 group.Through functional and pathway enrichment analysis of differential metabolites,it was found that SA and JANET signaling pathways were activated simultaneously in Arabidopsis thaliana resistance to Pst DC3000 induced by H.5-28,but mainly JANET signaling pathway-induced systemic resistance(ISR).Others include regulation of sulfur metabolism,glutathione metabolism and ascorbic acid metabolism pathways in Arabidopsis thaliana.The determination by HPLC-MS revealed that the contents of salicylic acid and jasmonic acid increased in H.5-28 group,Pst DC3000 group,and H.5-28 and Psi DC3000 co-group compared with blank control,but the contents of salicylic acid decreased and jasmonic acid increased in H.5-28 and Pst DC3000 co-group compared with Pst DC3000 group,which verified the results of metabolomics.3.In a further study,we performed a transcriptomic analysis to investigate the mechanism by which H.5-28induces resistanceto Pst DC3000 in Arabidopsis thaliana.The results showed that there were 86,5468 and 5465 differentially expressed genes in H.5-28 group,Pst DC3000 group,H.5-28 and Pst DC3000 co-group compared with the blank control.TheH.5-28 and Pst DC3000 co-grouphad 156 differentially expressed genes compared to the Pst DC3000 group.The differential expression genes were analyzed by GO and KEGG enrichment,and combined with genes expression of salicylic acid,jasmonic acid and ethylene related pathway in the previous data,the results revealed that H.5-28 induced Arabidopsis thaliana resistance to Pst DC3000,mainly by regulating the biosynthesis of flavonoids and lignin in phenylpropane biosynthesis.In conclusion,H.5-28 induces Arabidopsis thaliana resistance to Pst DC3000 by simultaneously activating of SA signaling pathway and JA/ET signaling pathway,but the JA/ET signaling pathway-mediated ISR is the major contributor.In addition,promoting the accumulation of flavonoids and lignin is the main defense measure.