| Small brown planthopper (Laodelphax striatellus) can transmit rice stripe virus (RSV) that results in serious damage to the rice. RSV is transmitted by the small brown planthoppers in a persistent and circulative manner, and the insects can pass the virus to the offsprings through eggs. The saliva of phloem feeders is a mediator of plant-(pathogen-) insect interactions and the salivary glands, the key organs for secretory substance production and delivery, are indispensable in insect feeding and pathogen transmission. When phloem feeders secrete watery saliva during intracellular penetration, virions interact with salivary components, and differences in the composition of the saliva of different insect species can result in differential transmission. Angiotensin converting enzyme (ACE) gene is expressed highly in aphid’s salivary glands. In this study the homologous ACE gene of L. striatellus was identified from the differentially expressed EST library genes. The full length of ACE transcript was obtained by the RACE PCR method. To investigate whether the ACE influences RSV-carrying and infection up rice by L. striatellus, dsRNA was injected to insects to inhibit the expression of ACE. Quantitative PCR was used to measure the expression levels of the seven proteins of RSV in insects as well as in rice plants. The results showed that126.5ng of dsRNA can efficiently inhibit ACE expression in insects and the efficiency was as high as90%. When the expression of ACE was inhibited, the expression of RSV’s CP was reduced while SP and RdRp were increased in insects.In rice plants fed by the ACE-knocked down planthoppers, all the seven RSV genes were up-regμlated except the RdRp gene, compared to the plants fed by intact planthoppers. These results indicate that the ACE is involved in the carry and transmission of RSV by small brown planthoppers, and this study provides a clue to disclose the molecular mechanisms underlying plant virus transmission by insects. |
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