Effects Of Wheat Infected With Plant Virus On Host Selection Behavior Of Wheat Aphid And Its Mechanism

Barley yellow dwarf virus(BYDV)(Luteoviridae: Luteovirus)is serious viral wheat disease in China.Barley yellow dwarf virus(BYDV)is the main virus that causes wheat virus disease in China.In recent years,the virus has severely spread in china.The virus can reduce wheat production by one-third and cause huge economic losses in epidemic year.BYDV-GAV and BYDV-PAV are the main strains of BYDV in China.Wheat aphid is an important pest on wheat and vectors of BYDV.Among them,Schizaphis graminum and Sitobion avenae are BYDV-GAV vectors,Sitobion avenae and Rhopalosiphum padi are BYDV-PAV vectors.In the field,wheat aphid and BYDV often occurring together.Previous studies have shown that BYDV can directly or through host plant affect the fitness,feeding behavior and enzyme activity of vectors/non-vectors to enhance wheat aphid and BYDV transmission.However,the selection behavior and mechanism of wheat aphid on wheat infected with BYDV are not clear.Based on previous studies,this study compared the host selection of vectors/non-vectors winged/wingless wheat aphid on infected /noninfected wheat.Comparison of volatiles between different wheat varieties at the seedling stage and ear stage of infected/noninfected of BYDV-GAV.In order to find out the effect and mechanism of infected wheat on host selection behavior of aphid,we studied the identification of the compounds in the laboratory.The main results were as follows:1.Through the selective experiments on the wheat wingless aphid at 12 h,36h,60 h on the susceptible / non-susceptible wheat,it was found that the BYDV-PAV virus caused the nonsusceptible wheat aphid to significantly increase the selectivity of the susceptible wheat at 12 h and 36 h.BYDV-PAV and BYDV-GAV caused the wingless BYDV-GAV susceptible Schizaphis graminum prefers noninfected plants at 12 h,36h and 60 h.Aphid feeding and virus interaction caused susceptible Schizaphis graminum prefers BYDV-GAV and BYDV-PAV infected wheat at 12 h.There was no selectivity between wingless nonsusceptible Sitobion avenae and wingless BYDV-PAV Rhopalosiphum padi.2.Through the selective experiments on the wheat winged aphid at 12 h,36h,60 h on the susceptible / non-susceptible wheat,it was found that BYDV-GAV caused the winged non-susceptible Rhopalosiphum padi prefers susceptible plants at 36 h,the winged nonsusceptible Sitobion avenae prefers infected plants at 12 h and 36h;Aphid feeding and BYDV-GAV interaction caused the winged non-susceptible Rhopalosiphum padi prefers susceptible wheat at 12 h and 60 h and winged non-susceptible Sitobion avenae at 60 h.There was no selectivity between winged susceptible /nonsusceptible BYDV-GAV Schizaphis graminum.3.The wheat volatiles on the seedling and ear stages in four different varieties of wheat plants under healthy,aphid-infected and BYDV-GAV-infected was collected and identified by the SPME-GC/MS method.The results showed that:(1)For the seedling stage wheat,compared with healthy plants and aphid-infected plants,the relative content of dodecane,tetradecane and pentadecane in the volatiles of BYDV-GAV-infected FAT35-27B3 is decreased significantly,2-methyl-dodecane and 3-methyl-tridecane disappear;the relative content of 2-methyltetracosane in volatile BYDV-GAV-infected FAT35-39A11 is decreased significantly,3-methyl-tridecane not detected;the relative content of 2-methyl-decane in volatile BYDV-GAV-infected PIG-78 DX is decreased significantly,the relative content of 1-octen-3-ol,2-ethyl-1-hexanol,2,6,10-trimethyl-dodecane,(E)-á-farnesene is significant-ly increased,3-methyl-tridecane not detected,and phenylethyl alcohol is added;the relative content of(E)-á-farnesene in volatile BYDV-GAV-infected AK58 is increased significantly.(2)For the ear stage wheat,compared with healthy plants and aphid-infected plants,the relative content of 3,7-dimethyl-undecane in the volatiles BYDV-GAV-infected FAT35-27B3 is increased significantly;the relative content of benzene acetaldehyde,4-chloro-octane,3,5-octane-2-one,tetradecane,7-methyl-pentadecane,isoshyobunone in the volatiles BYDV-GAV-infected FAT35-39A11 is increased significantly;the relative content of tetradecane,pentadecane,pentyl-cyclopropane and(E)-á-farnesene in volatile wheat PIG-78 DX is significantly increased,the relative content of nonane,undecane is decreased significantly,octane,1,3-dimethyl-benzene,1-octen-3-ol,octanal,2-ethyl-1-hexanol not detected;the relative content of 2-hexenal,3-methyl-tridecane,tetradecane in the volatiles BYDV-GAV-infected AK58 is increased significantly,the relative content of pentadecane,9-eicosyne,2-tridecaneone is decreased significantly,P-xylene,3,5,5-trimethyl-2-hexene,1-octen-3-ol,decane,(E)-2-octen-1-ol,3,5-octadien-2-one,phenethyl alcohol,2-ethylhexy-l acetate,naphthalene,and 2-methyl-naphthalene not detected.These show that BYDV-GAV can cause the changes of host plant volatiles composition,the changes of wheat volatiles in different periods and different varieties are different,so some compounds can be screened to verify the effect on aphid host selectivity.4.Seven candidate compounds at different concentrations were used to verify the selection behavior of non-infective wheat aphid.The results showed that 2-ethyltoluene,trans-2-Hexen-1-al,phenylacetaldehyde,phytoacetate,1,2,4,5-Tetramethylbenzene all showed significant effect on non-infective Schizaphis graminum.The attraction is the strongest when it is 0.1 ng /?L.Among them,the preference of cis-3-Hexenyl acetate is 80.9%,the 2-ethyltoluene,1,2,4,5-Tetramethylbenzene,phenylacetaldehyde and trans-2-Hexen-1-al are 67.4%,64.5%,63.1% and 63.1%.To sum up,non-infective wheat aphid prefers infected wheat,while infective wheat aphids prefer healthy wheat,which was complementary in wingless and winged wheat aphids.After BYDV infection,wheat volatiles changed significantly,and some compounds attracted aphids.This study can provide theoretical basis for the epidemic law of BYDV virus disease,and lay a foundation for the control of BYDV and wheat aphid.