Transmission of Tomato spotted wilt virus isolates able and unable to overcome tomato or pepper resistance by its vector Frankliniella occidentalis

[EN] Tomato spotted wilt virus (TSWV) causes serious diseases of many economically important crops. Disease control has been achieved by breeding tomato and pepper cultivars with the resistance genes Sw-5 and Tsw, respectively. However, TSWV isolates overcoming these genetic resistances have appeared in several countries. To evaluate the risk of spread of these resistance-breaking isolates, we tested their ability of transmission by the main vector of TSWV, the thrips Frankliniella occidentalis. We compared the transmission rate by thrips of six TSWV isolates of different biotype (able or unable to overcome this resistance in pepper and tomato), and with divergent genotype (A and B). Our results indicate that the transmission rate was related to the amount of virus accumulated in thrips but not to virus accumulation in the source plants on which thrips acquired the virus. No correlation was found between transmission efficiency by thrips and the genotype or between transmission efficiency and the ability of overcoming both resistances. This result suggests that resistance-breaking isolates have the same potential to be transmitted as the isolates unable to infect resistant tomato and pepper cultivars. This work was supported by grants RTA2008-00010-C03 and FEDER, and ACOMP/2009/103 financed by INIA and Generalitat Valenciana, respectively. D. E. D. was recipient of a FPU predoctoral fellowship from the Spanish Ministry of Science and Education and B. B. was supported by an INIA-CCAA contract. Fito´ and Seminis kindly provided the seeds of the tomato and pepper cultivars used in the experiment. We would like to thank Debora Mart ´ ´ınez and Dolores Com´ın for technical assistance, as well as Dr D. Peters (Wageningen University, the Netherlands) and Dr J. Contreras (Universidad Politecnica de Cartagena, Spain) ´ for kindly providing the TSWV isolate BR01 and a thrips colony, respectively. Drs E. Carbonell and J. Perez- Panades (IVIA) are thanked for statistical advice. Two anonymous referees improved a previous version of the manuscript. Debreczeni, DE.; Rubio, L.; Aramburu, J.; López Del Rincón, C.; Galipienso, L.; Soler Aleixandre, S.; Belliure, B. (2014). Transmission of Tomato spotted wilt virus isolates able and unable to overcome tomato or pepper resistance by its vector Frankliniella occidentalis. Annals of Applied Biology. 164:182-189. https://doi.org/10.1111/aab.12090