| Plasmopara viticola(Berk,et Curtis)Bert.et de Toni;the causal agent of grape downy mildew,and Uncinula necator(Schw.)Burr,the causal agent of powdery mildew, are different obligate parasite,and they can not be cultured on medium yet.Several methods were investigated for long-term preservation of sporangia in P.viticola.In this study,four Streptomyces strains,thirteen Pseudomonas fluorescens strains including the wild type strain WCS417r and its genetically modified derivatives,and four P.putida strains containing the wild type strain WCS358r,its siderophore-minus mutant JM218 and two genetically modified strains,were tested for their inhibiting effects on spore germination rate of Uncinula necator,and the preventive effects on grape powdery mildew and downy mildew using detached young grape leaves.Finally,induction of systemic acquired resistance was determined with different concentrations of salicylic acid against powdery mildew caused by Uncinula necator and downy mildew caused by Plasmopara viticola.The main results of this research are as follows.1.In this Study different concentrations of dimethylsulfoxide and glycerol were used to preserve sporangia of P.,viticola in different temperatures.The results showed that the sporangia preserved in 1.0%dimethylsulfoxide.were more virulent than those in 25% glycerol at -76℃,The proper concentrations of dimethylsulfoxide for preserving sporangia were 5%and 10%,with stronger pathogenicity than that preserved in 15%,20% and 25%dimethylsulfoxide;preserved in 5%and 10%dimethylsulfoxide at -76℃for 5d and 15d were more pathogenic to grape leaves than those kept at -20℃;The sporangia preserved at -76℃for 240 d in 10%dimethylsulfoxide lost their pathogeniciy,while those preserved in 5%dimethyl- sulfoxide retained their virulence to grape leaves,with disease rate of 56.3%after inoculation.2.To test separately the preventive effects of detached grape leaves soaking of dividing for Plasmopara viticola control experiment.The results indicated that Streptomyces rimosus and Streptomyces aureofaciens 2 streptomyces strains from 4 streptomyces strains were singled out,and their disease of Plasmopara viticola were both reduced 73.4 percentage point compared with that of the control;L1d6,L2d6 and L3d6 3 Pseudomonas from 13 transgene of WCS417r,their disease rate of Plasmopara viticola were reduced separately 40.0,66.7 and 70.0 percentage point compared with that of the control.WCS358::phz and WCS358::phl from,5 transgene of WeS358r,their disease rate of Plasmopara viticola were reduced separately 33.3 and 53.3 percentage point compared with that of the control.3.To test separately the Inhibition effects on spore germination of Uncinula necator, 2 streptomyces strains from 4 streptomyces strains were singled out,Their control efficacy reached 53.3%and 60.0%;L1d6,L2d6 and L3d6 3 Pseudomonas from 13 transgene of WCS417r,their control efficacy reached 65.0%,70.0%,and 80.0%;WCS358::phz and WCS358::phl from 5 transgene of WCS358r,there are both control efficacy reached 40%.Show significant difference atα=0.051evels(The same below).4.To test separately the preventive effects of detached grape leaves soaking of dividing for further Uncinula necator control experiment.The results indicated that Streptomyces rimbsus and Streptomyces aureofaciens 2 streptomyces strains from 4 streptomyces strains were singled out,Their control efficacy reached 53:3%and 60.0%; L1d6,L2d6 and L3d6 3 Pseudomonas from 13 transgene of WCS417r,their control efficacy reached 65.0%,70,0%,and 80.0%;WCS358::phz and WCS35S::phl from 5 transgene of WCS358r,there are both control efficacy reached 40%.5.Streptomyces rimosus,L3d6 and WCS358::phl fromthe cehtrifugate was detached grape leaves soaking of dividing for Plasmopdra.viticola control experiment.Streptomyces rimbsus from the centrifugate were not significantly reduced.23.3 percentagen point compared with that of the control.L3d6 and WCS358::phl from the centrifugate were not significant difference comparedwith that of the control.6.Preventive effects of different concentration of salicylic acid on Uncinula necator, It had strongest inhibitive ability against Uncinula necator were by grape branches with leaves dipped in 1mM of salicylic acid 2 days,:It had strongest inhibitive-ability against Plasmopara viticola by grape branches with leaves dipped in 3 mM of salicylic acid 2 days, but they were not significant compared with that of the control.The disease percentage of Uncinula necator and Plasmopara viticola were bothincreased when grape branches with leaves dipped in 5 mM of salicylic acid 2 days compared with that of the control.Salicylic acid of high concentration treatment grape branches with leaves has maybe toxicity,It made disease percentage of Uncinula necator and Plasmopara viticola were both increase.
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