The Chemical Composition And The Inhibition Of Amomum Tsao-ko Essential Oil Against Plant Pathogenic Fungi

The pesticide residues have become one of major factors that influence the quality and safety of agricultural products,which threaten human beings’ healthy seriously.Therefore,many scholars who committed to studying on the pesticides are paying more attention to develop the safe and natural pesticides which extract from plants.The plant essential oils belongs to an important part of botanical pesticides.Especially,it has been a hot spot that using plant essential oils as preservation fungicides in agricultural products such as fruit and vegetables.In this paper,the fungicidal activities of twleve plant essential oils at the concentration of 1g/L against the six plant pathogenic fungi were researched by determining the mycelium growth rates.The major chemical composition and its relative content of four plant essential oils which had good fungicidal activities were analyzed by GC-MS.The antifungal virulence of Amomum tsao-ko essential oil against six selected fungi were studied and the toxicity regression and median effect concentration was determined,respectively.We also defined the effect of Amomum tsao-ko essential oil on the Chitinase activity and SDH activity of Botrytis cinerea.The results showed as follows.1.The antifungal activitivies of the twelve plants essential oils by steam distillation extraction against Valsa mali,Colletotrichum gloeosporioides,Botrytis cinerea,Fusicladium plrinum,Physalospora piricpla and Colletotrichum coccodes by using mycelium growth rate method at the concentration of 1g/L was studied.The plant essential oils included the essential oils of Amomum tsao-ko,Thirteen-spice,Magnolia grandiflora,Fructus liquidambaris,Evodia rutaecarpa,Lysimachia sikokiana,Cortex mori,Ginkgo biloba,Phragmites australis,Rhizoma phragmitis,Typha angustata and Alternanthera philoxeorides.The results indicated that the essential oils of Amomum tsao-ko,Thirteenspice,Fructus liquidambaris and Magnolia grandiflora leaves showed good antifungal activitivies which the inhibition rates were 71.58~100%,57.13~100%,46.44%~81.52%,46.22%~ 71.06%,respectively.2.The chemical composition of four plant essential oils which had good inhibitory activities were analyzed by GC-MS and the quantitative determination was conducted using area normalization method.The GC-MS results exhibited that sixty-four components were identified and the major compounds in Amomum tsao-ko essential oil which were eucalyptol(27.24%),tetracyclo[3.3.1.0.1(3,9)]decan-10-one(9.18%),2-isopropylbenzaldehyde(6.36%)and citral(5.98%).Fifty-one components were identified in Thirteen-spice which the major compounds were anethole(59.68%),D-limonene(10.01%),Estra(4.55%),1-(3-methyl-2-butenoxy)-4-(1-propenyl)benzene(4.50%).Seventy components were identified in Fructus liquidambaris essential oil and the major compounds were caryophylleneoxide(10.65%),verbenone(8.83%),myrtenol(6.33%).Fify-six components were identified in Magnolia grandiflora leaves and the major compounds were β-elenmene(26.51%),longifolene(10.70%),myrcene(7.27%).3.Based on the Antifungal virulences of Amomum tsao-ko essential oil against the six plant fungi,it was acknowledged that the toxicity regressions to Valsa mali,Colletotrichum gloeosporioides,Botrytis cinerea,Fusicladium plrinum,Physalospora piricpla and Colletotrichum coccodes were y=2.0557x+0.4563(r=0.9627),y=3.3616x-3.9582(r= 0.9839),y=2.013x+0.2358(r=0.9945),y=2.3779x-1.5497(r=0.9599),y=2.7736x-2.8933(r=0.9783)and y=2.6761x-2.8781(r=0.9330),respectively.The value of EC50 were 0.1653g/L,0.4621g/L,0.2315g/L,0.5685g/L,0.6992g/L and 0.8618g/L,respectively.The inhibition of Amomum tsao-ko essential oil against Valsa mali was best when the inhibition against Colletotrichum coccodes was little worse.The good inhibitory activity of Amomum tsao-ko essential oil against the tested fungi exhibited that it possessed exploitation and application values in pesticide field.4.The effect of Amomum tsao-ko essential oil to the Chitinase activity of Botrytis cinerea at the concentration of 0.1 g/L,0.2 g/L and 0.3g/L was researched.The Chitinase activity of Botrytis cinerea under treatment with essential oil were always higher than CK.Besides,the Chitinase activity was higher apparently with the concentration increasing than the untrement.The SDH activities of Botrytis cinerea under the different concentration treatment including 0 g/L,0.05 g/L,0.1 g/L,0.15 g/L,0.2 g/L,0.3g/L which were 80.25 U/mgprot、77.12 U/mgprot 71.53 U/mgprot、62.08 U/mgprot、54.64 U/mgprot、47.19 U/mgprot.It was obviously that the SDH activities reduced with the concentration of Amomum tsao-ko essential oil adding.In a word,the essential oil inhibit the SDH activities.We could surmise two conclusions about the inhibition of the Amomum tsao-ko essential oil against Botrytis cinerea through the studies on the Chitinase and SDH activity.On one hand,the Amomum tsao-ko essential oil caused the huger for glucose to Botrytis cinerea and leaded to the degradation of cell wall due to the increasing of Chitinase activity.Then the cell’s integrity was damaged.On the other hand,the Amomum tsao-ko essential oil inhibit the SDH activity with leading to the handicap of electron transfer and respiratory oxide which caused the fungus growing slowly and dying.