Odorant-binding protein 2 is involved in the preference of Sogatella furcifera (Hemiptera: Delphacidae) for rice plants infected with the Southern rice black-streaked dwarf virus

Southern rice black-streaked dwarf virus, transmitted by the white-backed planthopper (Sogatella furcifera [Horvath]) (Hemiptera: Delphacidae) was first found in Guangdong Province, China. A previous study has demonstrated that the host plant preferences of S. furcifera are altered by infection with the virus, with virus-free S. furcifera preferring virus-infected rice plants over healthy rice plants, whereas viruliferous S. furcifera prefer uninfected plants. To test the hypothesis that odorant-binding proteins (OBPs) are involved in the preference of S. furcifera for virus-infected rice plants, we first compared the expression levels of SfurOBP2 and SfurOBP11 in virus-free and viruliferous S. furcifera. The results show that mRNA transcript of these 2 genes were significantly reduced in viruliferous S. furcifera. We then used RNAi-mediated gene silencing to confirm the function of these 2 odorant-binding proteins in host selection of S. furcifera. The results showed that silencing of the SfurOBP2 gene caused virus-free S. furcifera to no longer prefer virus-infected rice plants over uninfected rice plants, but the ability to locate host plants was maintained. These results indicate that SfurOBP2 appears to play a crucial role in the preference of S. furcifera for virus-infected rice plants.