Study On The Inhibition Mechanism Of Cinnamaldehyde On Phytophthora Capsici By Targeting PVC1

Phytophthora capsici Leonian is a kind of oomycete pathogen,which can infect many kinds of crops,such as solanaceae and cucurbitaceous plants.It has a wide range of damage and causes great damage to agricultural production.However,there is a lack of high efficiency and low toxicity fungicide for preventing and controlling this disease at present in agricultural.Preliminary laboratory study found that plant derived compounds cinnamaldehyde(CA)can control pepper phytophthora blight in the field efficiently and the inhibitory mechanism may relate to the reduction of intracellular calcium ion.In order to further clarify the molecular mechanism and action target of CA,the main study of this paper are as follows:1.The antifungal effect of CA on Phytophthora capsici in vitro.The study showed that the EC50 for CA against nearly seventy kinds of phytophthora capsici physiological races was 1.10 mmol/L.1.6 mmol/L CA treatment resulted in the abnormally broken mycelia of Phytophthora capsici and cell death indicated by PI staining.With the increase of the concentration of CA treatment,the content of malonaldehyde(MDA)was gradually increased,however,the content of glycerol in mycelium decreased gradually,and the mycelia membrane was damaged seriously.2.CA CA enhanced the resistance of pepper to phytophthora blight.Studies have shown that isolate NJ01 strain inoculation of pepper plants showed obvious disease symptoms,such as black brown atrophic sub-stem,plant lodging,leaf abscission,and decreased biomass.However,pepper seedlings inoculated with CA-treated NJ01 with increased fresh weight and chlorophyll content grew well without any obvious disease symptoms.Compared to the NJ01 inoculation alone,inoculation with CA-treated NJ01 resulted in the significant increases in the activities of anti-oxidative enzymes(e.g.CAT,POD,and SOD)and the contents of antioxidants(e.g.GSH and ASA).In conclusion,it can be speculated that pepper enhanced resistance to pepper phytophthora blight diseases by CA may attribute to the antifungal effect of CA and CA-modulated plant defense in pepper seedlings.3.Verification of CA targeting Phytophthora capsici PVC1 in yeast homologous mutant ?Yvc1.Cloning CA targeted gene of Pepper Phytophthora PVC1,and transferred into yeast homologous mutant ? Yvc1,then by yeast strain gradient dilution method complementary experiments,results showed that the wild yeast strain BY4741 is sensitive to CA and yeast homolog mutants ? Yvc1 reduced sensitivity to CA.When transferred Yvcl into Phytophthora capsici homologous mutant strain,complementary unit showed sensitive to CA.We studied on the three yeast strains:wild-type?mutant and complementary by detecting intracellular Ca2+ fluorescence,then statistics of fluorescence intensity and density,compared to the wild type strain,we found that Yvcl mutant strains were not sifinicantly changed in Ca2+ after CA treatment.When transferred Yvcl to the mutants,the intracellular Ca2+ was significantly decreased.It is showed that the PVC1 is indeed a target for CA efficiently inhibition Phytophthora capsici.4.Effect of CA treatment on the expression profile of Phytophthora capsici.By transcriptome sequencing technology,we found that 2575 Phytophthora capsici genes down regulated after CA treatment,the number of up-regulated genes was 956;these significantly expressed genes mostly involved in the process of cell metabolism pathway,biochemical synthesis of secondary metabolites,meiosis,MAPK signaling pathway,ABC transporters,amino acid metabolism,indicating that CA regulated a series of gene transcription changes in molecular level,thus affecting Phytophthora capsici physiological and biochemical metabolism and the infection of pepper as well.