Two alimentary canal proteins, Fo-GN and Fo-Cyp1, act in Western Flower Thrips, Frankliniella occidentalis TSWV infection

Authors: KHAN, FULGUNI - Andong National University; Stanley, David; KIM, YONGGYUN - Andong National University

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2023
Publication Date: 2/3/2023
Citation: Khan, F., Stanley, D.W., Kim, Y. 2023. Two alimentary canal proteins, Fo-GN and Fo-Cyp1, act in Western Flower Thrips, Frankliniella occidentalis TSWV infection. Insects. 14(2). Article 154. https://doi.org/10.3390/insects14020154.
DOI: https://doi.org/10.3390/insects14020154

Interpretive Summary: Some viruses are serious plant pests that cause tremendous losses of crop plants globally. The tomato spotted wilt virus causes massive losses of many crop plants, including tomato, red pepper, peanut around the world. It infects dozens of plant species. This virus is spread by a group of small insects known as thrips. The juvenile thrips acquire the virus by feeding on virus-infected plants. During thrip development, the virus moves from the gut to the salivary glands, where it reproduces. The adult thrips spread the virus by feeding on uninfected plants. Many scientists work on how the viruses survive and reproduce within their host thrips and how they spread to new host plants. The goal is to identify specific mechanisms that may be exploited to block the processes of acquiring the virus, the processes of viral reproduction and the processes transmitting the virus to new host plants. In this paper, we report on identification of two proteins that are produced by thrips. The virus uses these proteins to invade the thrip alimentary canals. Other researchers will use this new information in design of specific tools that may block production of the proteins and possibly block the virus ability to anchor itself to the trip proteins and thereby block the virus replication cycle. Blocking replication of plant viruses will save millions of dollars in crop losses and enable production of healthy vegetable crops for humanity at the global level.

Technical Abstract: Tomato spotted wilt virus (TSWV) is a plant virus that causes massive economic damage to high-valued crops. This virus is transmitted by specific thrips including the western flower thrips, Frankliniella occidentalis. TSWV is acquired by the young larvae during feeding on infected host plants. TSWV infects the gut epithelium through hypothetical receptor(s) and multiplies within the cells for subsequent horizontal transmission to other plant hosts via the salivary glands during feeding. Two alimentary canal proteins, glycoprotein (Fo-GN) and cyclophilin (Fo-Cyp1), have thought to be associated with the TSWV entry to the gut epithelium of F. occidentalis. Fo-GN possesses a chitin-binding domain, and its transcript was localized on the larval gut epithelium by fluorescence in situ hybridization (FISH) analysis. Phylogenetic analysis indicated that F. occidentalis encodes six cyclophilins, in which Fo-Cyp1 is closely related with a human cyclophilin A, an immune modulator. The Fo-Cyp1 transcript was also detected in the larval gut epithelium. Expression of these two genes was suppressed by feeding their cognate RNA interference (RNAi) to young larvaes. The RNAi efficiencies were confirmed by disappearance of the target gene transcripts from the gut epithelium by FISH analyses. The RNAi treatments directed to Fo-GN or Fo-Cyp1 prevented the typical TSWV titer increase after feeding the virus compared to control RNAi treatment. Our immunofluorescence assay using a specific antibody to TSWV documented the reduction of TSWV in larval gut and adult salivary gland after the RNAi treatments. These results support our hypothesis that the candidate proteins Fo-GN and Fo-Cyp1 act in TSWV entry and multiplication in F. occidentalis.