A severe symptom phenotype in pepper cultivars carrying the Tsw resistance gene is caused by a mixed infection between resistance-breaking and non-resistance-breaking isolates of Tomato spotted wilt virus

[EN] Pepper (Capsicum annuum) plants with the Tsw resistance gene showing unusually severe symptoms consisting of local lesions, chlorosis, stunting and systemic necrosis on the apical leaves were found in a commercial field in north eastern Spain in 2009. The presence of Tomato spotted wilt virus (TSWV) was confirmed in all diseased plants. After mechanical inoculation of Nicotiana glutinosa with infected field samples, biological clones of the virus were isolated from individual local lesions. These biological clones produced two different types of symptoms after inoculation on Tsw resistant pepper plants: (i) typical symptoms caused by resistance-breaking (RB) isolates characterized by chlorosis and stunting, and (ii) severe symptoms as observed in the field plants. Similar symptoms in pepper plants carrying the Tsw resistance gene were reproduced under controlled conditions, after simultaneous inoculation of RB and non-resistance-breaking (NRB) isolates. The NRB isolate was detected in a low proportion in the apical uninoculated leaves, whereas NRB isolates could not infect resistant pepper when inoculated alone. Co-infection by NRB and RB isolates induced disease synergism with systemic necrosis on the apical leaves. To our knowledge, this is the first case in which a synergic interaction between isolates of the same virus has been described, which has the ability to overcome a natural genetic resistance. This finding could have epidemiological implications for the management of TSWVWe thank M. Matas for locating commercial crops of pepper carrying the Tsw gene infected with TSWV and F. Aparicio for his excellent review of the manuscript. This research was supported by grants RTA2008-00010-C03 and RTA2013-00047-C02 from the Instituto Nacional de Investigaciones Agrarias (INIA).Aramburu, J.; Galipienso Torregrosa, L.; Soler Aleixandre, S.; Rubio Miguelez, L.; López Del Rincón, C. (2015). A severe symptom phenotype in pepper cultivars carrying the Tsw resistance gene is caused by a mixed infection between resistance-breaking and non-resistance-breaking isolates of Tomato spotted wilt virus. Phytoparasitica. 43:597-605. doi:10.1007/s12600-015-0482-1S5976054

A new Capsicum baccatum accession shows tolerance to wild-type and resistance-breaking isolates of Tomato spotted wilt virus

[EN] Tomato spotted wilt virus (TSWV) causes economically important losses in many crops, worldwide. In pepper (Capsicum annuum), the best method for disease control has been breeding resistant cultivars by introgression of gene Tsw from Capsicum chinense. However, this resistance has two drawbacks: (a) it is not efficient if plants are infected at early growth stages and under prolonged high temperatures, and (b) it is rapidly overcome by TSWV evolution. In this work, we selected and evaluated a new accession from Capsicum baccatum, named PIM26-1, using a novel approach consisting in measuring how three parameters related to virus infection changed over time, in comparison to a susceptible pepper variety (Negral) and a resistant (with Tsw) accession (PI-159236): (a) The level of resistance to virus accumulation was estimated as an opposite to absolute fitness, W=er , being r the viral multiplication rate calculated by quantitative RT-PCR; (b); the level of resistance to virus infection was estimated as the Kaplan–Meier survival time for no infection using DAS-ELISA to identify TSWV-infected plants; (c) the level of tolerance was estimated as the Kaplan–Meier survival time for no appearance of severe symptoms. Our results showed that the levels of both resistance parameters against TSWV wild type (WT) and Tsw-resistance breaking (TBR) isolates were higher in PIM26-1 than in the susceptible pepper variety Negral and similar to the resistant variety PI-159236 against the TBR isolate. However, PIM26-1 showed a very high tolerance (none of the plants developed severe symptoms) to the WT and TBR isolates in contrast to Negral for WT and TBR or PI-159236 for TBR (most TSWV-inoculated plants developed severe symptoms). All this indicate that the new accession PIM26-1 is a good candidate for breeding programmes to avoid damages caused by TSWV TBR isolates in pepperD.E.D. was the recipient of a fellowship FPU from the Spanish Ministry of Education, Culture and Sports. This work was funded in part by INIA projects RTA2008-00010-C03 and RTA2013-00047-C02. We thank E. Lazaro and Dr. C. Armero (Dept. Statistics and Operational Research, University of Valencia) for helpful suggestions on statistics and Drs. N. Duran and J. Guerri (IVIA) for critical reading of the manuscript.Soler Aleixandre, S.; Debreczeni, DE.; Vidal, E.; Aramburu, J.; López Del Rincón, C.; Galipienso Torregrosa, L.; Rubio Miguelez, L. (2015). A new Capsicum baccatum accession shows tolerance to wild-type and resistance-breaking isolates of Tomato spotted wilt virus. Annals of Applied Biology. 167:343-353. doi:10.1111/aab.12229S34335316

First report of a natural infection of Eggplant mottled dwarf virus in Podranea ricasoliana showing leaf intervenial yellowing

Alfaro Fernández, AO.; Font San Ambrosio, MI.; Hernández Llopis, D.; Galipienso Torregrosa, L.; Rubio, L. (2016). First report of a natural infection of Eggplant mottled dwarf virus in Podranea ricasoliana showing leaf intervenial yellowing. Plant Disease. 100(9):1955-1955. doi:10.1094/PDIS-02-16-0192-PDNS19551955100

Situación actual de la enfermedad del bronceado después de 25 años desde su introducción en España

[ES] La enfermedad del bronceado del tomate, causada por el Tomato spotted wilt virus (TSWV), fue detectada por primera vez en España en el año 1988. A partir de esa fecha, el virus se propagó por todo el litoral mediterráneo y se convirtió en el principal factor limitante para el cultivo de algunas especies hortícolas. La introducción de resistencias naturales al virus en algunos cultivos comerciales resolvió el problema, pero solo temporalmente ya que en el año 2002 aparecieron variantes virales capaces de superarlas. No obstante, la dispersión de alguna de estas variantes está siendo limitada. La variabilidad genética del virus, la identificación de los determinantes genéticos responsables de la rotura de las resistencias, la eficiencia y adaptabilidad de las nuevas variantes virales y las interacciones entre ellas, son aspectos que se discuten en este trabajo, para tratar de explicar la situación actual de la enfermedad y su posible evolución en el futuro.Esta investigación se ha realizado con la aportación económica de los proyectos RTA04-004-C2 y RTA2008-00010-C03 del INIA y ACOMP/2011/078 de la Generalitat ValencianaAramburu, J.; Galipienso Torregrosa, L.; López Del Rincón, C.; Soler Aleixandre, S.; Debreczeni, DE.; Belliure Ferrer, BR. (2013). Situación actual de la enfermedad del bronceado después de 25 años desde su introducción en España. Phytoma España. (251):23-30. http://hdl.handle.net/10251/63983S233025

First report of Tomato leaf curl New Delhi virus infecting cucurbits in the Canary Islands

This work was supported by the Institute Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) grant RTA2017-00061-C03-02 cofunded with FEDER.Espino, A.; Botella, M.; Otazo-González, H.; Alfaro Fernández, AO.; Font San Ambrosio, MI.; Galipienso-Torregrosa, L.; Rubio Migélez, L. (2019). First report of Tomato leaf curl New Delhi virus infecting cucurbits in the Canary Islands. Plant Disease. 103(7):1798-1798. https://doi.org/10.1094/PDIS-01-19-0054-PDNS17981798103

Complete sequence of three different biotypes of Tomato spotted wilt virus (wild type, tomato Sw-5 resistance-breaking and pepper Tsw resistance-breaking) from Spain

[EN] Tomato spotted wilt virus (TSWV) is worldwide spread and causes production losses in many important horticultural crops such as tomato and pepper. Breeding resistant cultivars has been the most successful method for disease control. So far, only two resistance genes have been found to confer resistance against a wide spectrum of TSWV isolates: Sw-5 in tomato and Tsw in pepper. However, TSWV resistance-breaking isolates have emerged in different countries after a few years of implementation of resistant cultivars. In this paper we report the first complete nucleotide sequence of three TSWV isolates from Spain with different biotypes according to the ability of overcoming resistance: LL-N.05 (wild type, WT), Pujol1TL3 (Sw-5 resistance breaking, SBR) and PVR (Tsw resistance-breaking, TBR). The genome of these TSWV isolates consisted of three genomic segments: L (8913-8914 nt), M (4752-4825 nt) and S (2924-2961 nt). Variations in nucleotide sequences and genomic lengths among the different virus biotypes are reported here. Phylogenetic analysis of the five TSWV open reading frames showed evidences of reassortment between genomic segments of LL-N.05 and Pujol1TL3, which was supported by analysis with different recombination-detecting algorithms. Genetic distances were uncorrelated to biotype, host or geographic location.D.E.D. was the recipient of a predoctoral FPU fellowship from the Spanish Ministry of Education, Culture and Sports. This work was funded in part by grants RTA2008-00010-C03 and RTA2013-00047-C02 from Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) and grants ACOMP/2009/103, ACOMP/2010/085 and ACOMP/2011/078 from Generalitat Valenciana. Work in the J.A.D. laboratory was supported by grant BIO2011-26741 from the Spanish Ministerio de Economia y Competitividad. We thank Veronica Aragones (IBMCP, CSIC-UPV) for technical assistance.Debreczeni, DE.; López Del Rincón, C.; Aramburu, J.; Daros Arnau, JA.; Soler Aleixandre, S.; Galipienso Torregrosa, L.; Falk, BW.... (2015). Complete sequence of three different biotypes of Tomato spotted wilt virus (wild type, tomato Sw-5 resistance-breaking and pepper Tsw resistance-breaking) from Spain. Archives of Virology. 160:2117-2123. https://doi.org/10.1007/s00705-015-2453-8S2117212316

Detection, discrimination and absolute quantitation of Tomato spotted wilt virus isolates using real time RT-PCR with TaqMan®MGB probes

A quantitative real-time reverse transcription-polymerase chain reaction (RT-qPCR) procedure using a general primer set and three TaqMan (R) MGB probes was developed for general and genotype-specific detection and quantitation of the genomic M segment of Tomato spotted wilt virus (TSWV). Standard curves using RNA transcripts homologous to the three probes allowed reproducible quantitative assays with a wide dynamic range (10(3)-10(10) TSWV M segment RNA copies/ng of total RNA) and high sensitivity. This protocol was assayed with a battery of TSWV isolates, covering the range of the present known genetic variation, in single and/or mix infections in three plant hosts, as well as in the thrips vector Frankliniella occidenialis. This quantitative detection assay will be a valuable tool for molecular biology and epidemiology studies, diagnosis and disease control.This work was supported by grants INIA RTA2008-00010-C03 and Generalitat Valenciana ACOMP/2009/103 and ACOMP/2010/085. D.E. Debreczeni is the recipient of a FPU pre-doctoral fellowship from MEC and B. Belliure was supported by a INIA-CCAA contract. We thank I. Ferriol, Dr. S. Ambros and Dr. A. Olmos for technical advice; Dolores Comin for technical assistance; Dr. D. Peters and Dr. J. Contreras for kindly providing the TSWV isolate BR01 and a thrips colony, respectively; and Daniel R. Pearce for English revision.Debreczeni, DE.; Ruiz Ruiz, S.; Aramburu, J.; López Del Rincón, C.; Belliure Ferrer, BR.; Galipienso Torregrosa, L.; Soler Aleixandre, S.... (2011). Detection, discrimination and absolute quantitation of Tomato spotted wilt virus isolates using real time RT-PCR with TaqMan®MGB probes. Journal of Virological Methods. 176(1-2):32-37. https://doi.org/10.1016/j.jviromet.2011.05.027S32371761-