Expressions And Conditions Of Induced Resistance To Fusarium Oxysporum In The Chinese Cucumber By A Pyrazolopyrimidine Derivative

Two compounds with China's independent intellectual property rights were screened.One is pyrazolopyrimidine derivative?BDO-1?,and the other is pyridazinone derivative?PDZ-1?.The induced resistance of the two compounds to 7 kinds of vegetable diseases had been found in broad-spectrum plant disease resistance tests.In particular,BDO-1 showed obvious induced resistance to cucumber fusarium wilt disease.In order to explore its possible mechanisms of induced resistance to Fusarium oxysporum of cucumber by BDO-1,confocal laser scanning microscope,Real time-PCR and proteomics were used synthetically in this paper.The results were following below.1.Broad-spectrum induced disease resistance and the inducing techniques of BDO-1 and PDZ-1 were clarified.The effect of induced resistance of BDO-1 on Pseudomonas syringae pv.lachrymans,Fusarium oxysporum f.sp.cucumerinum and Pseudoperospora cubensi of cucumber by foliar spraying were ranged form 48.82%to 78.5%.The effect of induced resistance of PDZ-1 on Pseudomonas syringae pv.lachrymans,Corynespora cassiicola and Pseudoperospora of cucumber by foliar spraying were in the range from 35.65%to 63.81%.The effect of induced resistance was not increasing with the increasement of the increment of these two compounds.Bioactivity in vitro of BDO-1 and PDZ-1showed that there is no inhibition against F.oxysporum and C.graminearum form these two compounds.The optimal induction conditions for BDO-1 and PDZ-1 were as bellow:5 times at an induction interval of 5 days,at a concentration of 10 mg/L.2.It was indicated that the systemic acquired resistance of cucumber to Fusarium oxysporum can be induced by BDO-1.The H₂O₂ content in the cucumber pretreated by BDO-1 was enhanced after the inoculation of F.oxysporum one day.Then the accumulation of callose was occurred at the cucumber roots.BDO-1 can enhance the activity of superoxide dismutase?SOD?and catalase?CAT?at 3 day post-inoculation.We observed that the colonization of F.oxysporum in the roots of cucumber which was pretreated by BDO-1 progressed more slowly at 7dpi by confocal laser scanning microscope.Real-time polymerase chain reaction?Real-time PCR?revealed that BDO-1 can also induce up-regulated expression of the CAT,PAL,LOX and EIN2 genes in the cucumber,and the expression have to peaked at 7dpi.The expression of PR1 and SOD genes had declined from their peaks after 1 dpi.3.Proteomics revealed that the salicylic acid pathway plays a major role in the cucumber systemic acquired resistance to F.oxysporum induced by BDO-1.In this study,we introduced the technology of label-free proteomics to determine differentially expressed proteins after BDO-1 treatment.About 3685secretome proteins changed in abundance indicating a massive activation of defence mechanisms with BDO-1.The expression of proteins that related to plant resistance,such as structural molecule activity proteins,antioxidant activity proteins,signaling proteins could up-regulated by BDO-1.These changes increase plant disease resistance.Using KEGG combined with bioinformatics analysis,we constructed a protein pathway of cucumber systemic acquired resistance to F.oxysporum induced by BDO-1.In the course of disease resistance,peroxisome,MAPK signaling pathway,Ca²⁺signaling pathway,phenylalanine metabolism,and salicylic acid pathway,were all affected by BDO-1,which ultimately led to the enhancement of cucumber systemic acquired resistance.The signal pathway of BDO-1induced resistance of cucumber at the protein level was as bellow:salicylic acid pathway plays a major role,and jasmonic acid/ethylene pathway plays a supporting role.