Resistance breaking tospoviruses in Europe: What is the current situation?

Tospoviruses are now included in the order Bunyavirales, family Tospoviridae, genus Orthotospovirus. Currently four tospovirus species are reported in Europe: Tomato spotted wilt orthotospovvirus (TSWV), Impatiens necrotic spot orthotospovirus, (INSV), Iris yellow spot orthotospovirus, (IYSV) and Polygonum ringspot orthotospovirus (PolRSV). Only viruses of the first three species cause diseases in vegetable crops, often being a limiting factor in crop production. Viruses of the first two species are efficiently transmitted by Frankliniella occidentalis and TSWV is by far the most damaging tospovirus causing important diseases in pepper, tomato, artichoke and lettuce crops worldwide. By contrast IYSV is transmitted by Thrips tabaci, mostly in onion, garlic and leek crops in many countries in Europe and worldwide. Resistance genes for TSWV are reported for pepper, tomato and lettuce, but only those for pepper and tomato have been extensively deployed in Europe. Molecularly, both the resistance genes and their corresponding virus encoded avirulence factors have been characterized in detail. We are reporting on the occurrence of resistance breaking strains in open fields throughout southern and central Europe, for both pepper and tomato crops. Furthermore we will report on the efforts to obtain new resistance for breeding purposes through traditional approaches, in particular for pepper and tomato. We will also report on the necessity of new resistance in other vegetable crops.