The Change Of Volatiles From Rice Seedlings Induced By SRBSDV And Their Effects On The Host Selection Behavior Of Sogatella Furcifera

Southern rice black-streaked dwarf virus(SRBSDV)is a persistent virus transmitted by the whitebacked planthopper(WBPH),Sogatella furcifera,among rice plants.It was reported that virus-free WBPHs prefer SRBSDV-infected rice plants,while virus-infected WBPHs prefer to choose SRBSDV-uninfected rice plants(only test one rice variety),it is still unknown what the mechanisms caused the selection differences.The behavioral responses of WBPHs between SRBSDV-uninfected rice plants and SRBSDV-infected rice plants(3 rice varieties)were tested by using olfactometer.The volatiles from SRBSDV-infected and uninfected plants were collected by using the dynamic headspace,and analyzed on GC-MS,respectively.The behavioral responses of WBPHs to the volatiles were tested by using olfactometer.The expression of the relevant genes involving in terpenoids biosynthetic pathways was analysed by q-PCR.This research aims to find the active volatiles,and explore the mechanism how SRBSDV controlled the behavior of WBPHs by regulating the volatiles of rice plants.The results were as follow:1.The host preference of WBPHs between SRBSDV-uninfected rice plants and SRBSDV-infected rice plants was tested,the results showed that 67% WBPHs fed on SRBSDV-uninfected plants preferred SRBSDV-infected rice plants,while 61.5% WBPHs fed on SRBSDV-infected plants preferred SRBSDV-uninfected rice plants.Our research indicated that behavioral differences generally exited in 3 rice varieties,which was helpful for the transmission of SRBSDV.2.Thirty-six volatile compounds,belonging to 11 categories,were detected from the uninfected plants.Thirty-seven compounds,belonging to 12 categories,were detected from the SRBSDV-infected plants.Twelve compounds,including n-hexadecane,didecyl ether,butyl octyl phthalate,n-octadecane,diisobutyl adipate(DA),pentadecanal,methyl hexadecanoate(MH),cedrol,2-methylhexacosane,benzophenone,n-eicosane and plant alcohol,were detected in the infected plants but not in the uninfected plants.Meanwhile,six compounds,i.e.,1-tricosene,octadecanal,naphthalene,perhydrofarnesyl acetone,lauryl alcohol and butylated hydroxytoluene(BHT),which were detected both in the infected and uninfected plants,had significant differences in their content.3.In olfactory selection experiments,plant alcohol exhibited repellent activity against WBPHs at the concentration of 50 μL/L and 500 μL/L,cedrol exhibited repellent activity against WBPHs at the concentration of 500 μL/L.4.The expression levels of the relevant genes involving in MVA pathways and MEP pathways were relevant to rice plants fed by WBPHs.The expressions of DMD gene and IP gene up-regulated when rice plants were fed by viruliferous WBPHs after 96 h,the two genes’ up-regulation may be relative to terpenoids(plant alcohol and cedrol)only detected in SRBSDV-infected plants,the mechanism of volatiles release regulated by gene is not clear,more researches are needed to be done.