title: The non-canonical tomato yellow leaf curl virus recombinant that displaced its parental viruses in southern Morocco exhibits a high selective advantage in experimental conditions.
abstract: Recombination events are frequently inferred from the increasing number of sequenced viral genomes, but their impact on natural viral populations has rarely been evidenced. TYLCV-IS76 is a recombinant (Begomovirus,Geminiviridae) between the Israel strain of tomato yellow leaf curl virus (TYLCV-IL) and the Spanish strain of tomato yellow leaf curl Sardinia virus (TYLCSV-ES) that was generated most probably in the late 1990s in southern Morocco (Souss). Its emergence in the 2000s coincided with the increasing use of resistant tomato cultivars bearing the Ty-1 gene, and led eventually to the entire displacement of both parental viruses in the Souss. Here, we provide compelling evidence that this viral population shift was associated with selection of TYLCV-IS76 viruses in tomato plants and particularly in Ty-1-bearing cultivars. Real-time quantitative PCR (qPCR) monitoring revealed that TYLCV-IS76 DNA accumulation in Ty-1-bearing plants was significantly higher than that of representatives of the parental virus species in single infection or competition assays. This advantage of the recombinant in Ty-1-bearing plants was not associated with a fitness cost in a susceptible, nearly isogenic, cultivar. In competition assays in the resistant cultivar, the DNA accumulation of the TYLCV-IL clone - the parent less affected by the Ty-1 gene in single infection - dropped below the qPCR detection level at 120 days post-infection (p.i.) and below the whitefly vector (Bemisia tabaci) transmissibility level at 60 days p.i. The molecular basis of the selective advantage of TYLCV-IS76 is discussed in relation to its non-canonical recombination pattern, and the RNA-dependent RNA polymerase encoded by the Ty-1 gene.
authors.affiliation: CIRAD-INRA-SupAgro, UMR BGPI, CIRAD, TA A -54K, Campus International de Baillarguet, F-34398 Montpellier, France.|Ecole Nationale d'Agriculture de Meknès, BPS 40, Meknès, Morocco.|Faculté des Sciences de Meknès BP 11201, Avenue Zitoune, Meknès, Morocco.
authors.forename: Zineb
authors.initials: Z
authors.lastname: Belabess
authors.affiliation: CIRAD-INRA-SupAgro, UMR BGPI, CIRAD, TA A -54K, Campus International de Baillarguet, F-34398 Montpellier, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Peterschmitt
authors.affiliation: CIRAD-INRA-SupAgro, UMR BGPI, CIRAD, TA A -54K, Campus International de Baillarguet, F-34398 Montpellier, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Granier
authors.affiliation: Ecole Nationale d'Agriculture de Meknès, BPS 40, Meknès, Morocco.
authors.forename: Abdessalem
authors.initials: A
authors.lastname: Tahiri
authors.affiliation: Faculté des Sciences de Meknès BP 11201, Avenue Zitoune, Meknès, Morocco.
authors.forename: Abdelali
authors.initials: A
authors.lastname: Blenzar
authors.affiliation: CIRAD-INRA-SupAgro, UMR BGPI, CIRAD, TA A -54K, Campus International de Baillarguet, F-34398 Montpellier, France.
authors.forename: Cica
authors.initials: C
authors.lastname: Urbino
mesh_terms: D000818:Animals; D053839:Begomovirus / Q000235:genetics* / Q000502:physiology; D006430:Hemiptera / Q000502:physiology / Q000821:virology; D007303:Insect Vectors / Q000502:physiology / Q000821:virology; D018551:Solanum lycopersicum / Q000821:virology*; D009018:Morocco; D010935:Plant Diseases / Q000821:virology*; D011995:Recombination, Genetic