Physiological And Molecular Mechanisms Of Control Of Cucumber Fusarium Wilt By Trichoderma Harzianum

Cucumber is one of the main vegetables cultivated in China.Cucumber wilt disease is a worldwide soil-borne disease.The pathogen is the cucumber specialized Fusarium oxysporum f.sp.Cucumerinum(FOC),and its incidence is severe.Up to 60%to 70%,limiting the quality and yield of cucumber.In recent years,the resistance of cucumber to Fusarium wilt induced by Trichoderma has become a research hotspot,but its induced disease-resistance genes and metabolic regulatory networks are not yet clear.This paper inducing disease resistance in plants.Using high-throughput gene sequencing technology,we analyzed the results of transcriptome sequencing,screened and performed fluorescent quantitative PCR validation,and finally obtained Trichoderma spp.The key gene that functions in.The result is as follows:1 T.harzianum promotion and inducticon of plant disease resistanceThe results of the study showed that T.harzianum TM has a significant growth promoting effect on cucumber.According to the live staining of DAB and NBT in roots,the staining color of FO treatment was significantly deeper than other treatments.However,the color of roots of pre-inoculated Trichoderma re-inoculated FO was lighter,indicating that the root infection and damage of cucumber treated with Fusarium oxysporum were serious.It showed that the TM strain could effectively resist the infection of Fusarium oxysporum and reduce the damage of the pathogen to the plants.2 Effect of Redox Signals on T.harzianum in Cucumber Fusarium Wilt ResistanceCompared with plants that had only been inoculated with Fusarium wilt,Trichoderma TM inoculated with Fusarium oxysporum significantly increased AsA,GSH content,AsA/DHA,GaILDH,?-GCS,and GSNOR activity in cucumber roots,but H2O2,O2·-,MDA,NO,SNOs,and GSNO were significantly reduced.At the same time,the activities of G6PDH,6PGDH,NADP-ICDH and NADP-ME in the pentose phosphate pathway after inoculation with Trichoderma were investigated.This indicates that Trichoderma can increase oxidative stress and reactive nitrogen stress in cucumber roots by activating the AsA-GSH cycle and the pentose phosphate pathway-related enzyme activity and reducing nitrosoglutathione reductase activity.3 Analysis and verification of transcriptome sequencing resultsBased on the transcriptome analysis of 12 samples,a total of 106.95 Gb Clean Data was obtained.The clean data of each sample reached 7.71 Gb,and the percentage of Q30 bases was 92.58%or more,indicating that the transcriptome sequencing results were available.Based on the cucumber reference genome sequence,the sequencing results were compared and the total alignment was 715,281,854 reads.The average matching rate was 74.07%.Compared with CK in TM treatment group,TM+FO treatment group and FO treatment group,1,272,1,042 and 1,249 differentially expressed genes were obtained,respectively,and the common differentially expressed genes were 145.Based on the COG,GO and KEGG databases,the annotation information obtained from the sequence comparison was used to analyze the differential expression of the above 145 genes.Ten differentially expressed genes related to resistance to the plants induced by Trichoderma harzianum were initially screened and verified for expression.The results showed that 8 genes were identical to the transcriptome data analysis results,which were Csa1G021940,Csa1G660200,Csa6G338660,Csa2G000790,Csa5G470560,Csa3G730980,Csa5G072680 and Csa3G099650.This study demonstrated that Trichoderma can induce the expression of disease-resistance related genes in cucumber,and screened eight key genes related to the induction of cucumber resistance to Fusarium wilt by Trichoderma harzianum.