The Research Of The Mechanism Of Improved-biocontrol Agent F1-35 Against Fusarium Wilt On Watermelon

Watermelon(Citrullus lanatus)is one of the most important fresh fruit worldly.However,watermelon is seriously damaged by Fusarium oxysporum f.sp.niveum(Fon),which was called Fusarium wilt.The precious research showed that the improved-biocontrol agent F1-35 had a high control-efficiency against Fon,and had the ability to promote the growth of watermelon seedling.In this study,through histological observation by WGA-AF488 staining,ptoteomics and qRT-PCR analysis,the interactions of F1-35 and watermelon seedling were researched,and the results were mainly as following:1.The control-efficiency of F1-35 against watermelon Fusarium wilt was tested in green house,and the result was 61.7 %.2.Paring assay analysis indicated that the strain F1-35 did not inhibit the normal growth of watermelon Fusarium wilt pathogen Fon,because the spores and mycelial growth of Fon were not changed under microscope observation.3.The interaction between F1-35 and watermelon root was observed.And the results showed that the strain F1-35 had the ability to infect and colonize into root of watermelon at more sites and faster than Fon.4.The proteomes of 12 h,24h and 48 h were researched.Compared to CK,differentially expressed proteins were obtained 1109.12 h root sample to CK,there were 184 differentially expressed proteins.24 h root sample to CK,there were 412 differentially expressed proteins.And 48 h root sample to CK,413 differentially expressed proteins were identified.Gene ontology analysis revealed that most differentially expressed proteins were existed in single-organismal process,metabolic process,singleorganism and cellular process in biological process.And in molecular function,binding,catalytic activity and transporter activity got lot differentially expressed proteins.Also some differentially expressed proteins belong to cell,organelle,membrane and cell part in cellular component.Then the KEGG pathway analysis showed that most differentially expressed proteins occuerd in glycolysis /gluconeogenesis,carbon metabolism,biosynthesis of amino acids,pyruvate metabolism,phenylpropanoid biosynthesis,RNA transport,purine metabolism,plant-pathogen interaction,mRNA surveillance pathway,ribosome,alanine,aspartate and glutamate metabolism,PI3K-Akt signaling pathway andarginine and proline metabolism.5.The proteins,higher 1.5 fold or lower 0.8 fold than CK,were chosen to analyze.Then,the up-regulated proteins were associated with copy distable soil environment,drought stress,JA/SA associated proteins,PR5 and Glyceraldehyde-3-phosphate dehydrogenase.And the down-regulated proteins were gibberellin-binding protein(Gip),auxin repressing protein(Arp)and a negative-regulated resistance protein,WRKY 17,which was a negative protein to JA,and negative-regulated resistance protein.So here was a hypothsis that F1-35 triggered the SA and JA pathway of watermelon against Fusarium wilt.6.To validate the hypothsis,the quantity real time PCR(qRT-PCR)was used to analyze the PR1?PR3?PAL?LOX1?CTR1?NPR1 genes' expression level,which were the key gene on JA/SA pathway.And the results showed those genes,positive correlation to JA/SA were up-expression,like PR1?PR3?PAL?LOX1 and NPR1,and the negative associated gene,CTR1,to JA/ET was down-expression in root,stem and leaf after reated with F1-35 in different time.In conclusion,the improved biocontrol agent F1-35 could enhance the resistance of watermenlon to Fon through space occupation and mainly triggered JA and SA pathway.