title: The Whitefly Bemisia tabaci Knottin-1 Gene Is Implicated in Regulating the Quantity of Tomato Yellow Leaf Curl Virus Ingested and Transmitted by the Insect.
abstract: The whitefly Bemisia tabaci is a major pest to agricultural crops. It transmits begomoviruses, such as Tomato yellow leaf curl virus (TYLCV), in a circular, persistent fashion. Transcriptome analyses revealed that B. tabaci knottin genes were responsive to various stresses. Upon ingestion of tomato begomoviruses, two of the four knottin genes were upregulated, knot-1 (with the highest expression) and knot-3. In this study, we examined the involvement of B. tabaci knottin genes in relation to TYLCV circulative transmission. Knottins were silenced by feeding whiteflies with knottin dsRNA via detached tomato leaves. Large amounts of knot-1 transcripts were present in the abdomen of whiteflies, an obligatory transit site of begomoviruses in their circulative transmission pathway; knot-1 silencing significantly depleted the abdomen from knot-1 transcripts. Knot-1 silencing led to an increase in the amounts of TYLCV ingested by the insects and transmitted to tomato test plants by several orders of magnitude. This effect was not observed following knot-3 silencing. Hence, knot-1 plays a role in restricting the quantity of virions an insect may acquire and transmit. We suggest that knot-1 protects B. tabaci against deleterious effects caused by TYLCV by limiting the amount of virus associated with the whitefly vector.
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel. aliza.hariton@mail.huji.ac.il.
authors.forename: Aliza
authors.initials: A
authors.lastname: Hariton Shalev
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel. iris.sobol@mail.huji.ac.il.
authors.forename: Iris
authors.initials: I
authors.lastname: Sobol
authors.affiliation: Institute of Plant Protection, Department of Entomology, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel. ghanim@volcani.agri.gov.il.
authors.forename: Murad
authors.initials: M
authors.lastname: Ghanim
authors.affiliation: Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China. shshliu@zju.edu.cn.
authors.forename: Shu-Sheng
authors.initials: SS
authors.lastname: Liu
authors.affiliation: Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel. hanokh.czosnek@mail.huji.ac.il.
authors.forename: Henryk
authors.initials: H
authors.lastname: Czosnek
mesh_terms: D000818:Animals; D053839:Begomovirus / Q000276:immunology / Q000302:isolation & purification*; D057771:Cystine-Knot Miniproteins / Q000235:genetics*; D015870:Gene Expression; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006430:Hemiptera / Q000276:immunology / Q000821:virology*; D019476:Insect Proteins / Q000235:genetics*; D007303:Insect Vectors / Q000276:immunology / Q000821:virology*; D015854:Up-Regulation
chemical_list: D057771:Cystine-Knot Miniproteins; D019476:Insect Proteins
keywords: geminiviruses; gene silencing; insect-plant-virus interaction; knottin genes