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Variation in Infection Capacity and in Virulence Exists Between Genotypes of Sugarcane yellow leaf virus

March 2007 , Volume 91 , Number  3
Pages  253 - 259

Youssef Abu Ahmad , Cirad, UMR Agro.M-Cirad-Inra Biologie et Génétique des Interactions Plante-Parasite (BGPI), Montpellier Cedex 5, F-34398 France ; Laurent Costet , Cirad, UMR Cirad-Universitéde La Réunion Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint-Pierre, La Réunion, F-97410 France ; Jean-Heinrich Daugrois , Cirad, UPR Multiplication Végétative, Petit-Bourg, Guadeloupe, F-97170 France ; Samuel Nibouche , Cirad, UMR Cirad-Université de La Réunion PVBMT, Saint Pierre, La Réunion, F-97410 France ; Philippe Letourmy , Cirad, UPR Aide à la Décision et Biostatistique, Montpellier Cedex 5, F-34398, France ; and Jean-Claude Girard and Philippe Rott , Cirad, UMR Agro.M-Cirad-Inra BGPI, Campus International de Baillarguet, TA 41/K, Montpellier Cedex 5, F-34398 France



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Accepted for publication 19 September 2006.
ABSTRACT

Two experiments, one in Guadeloupe and one in Réunion Island, were performed to transmit different genotypes of Sugarcane yellow leaf virus (SCYLV) to eight sugarcane cultivars differing in resistance to infection by the virus and to yellow leaf. Transmission was attempted from SCYLV-infected sugarcane plants or leaves to healthy tissue-cultured plantlets grown in vitro and with the aphid vector Melanaphis sacchari. After inoculation and elimination of insects with an insecticide, plantlets were transferred to Montpellier, France and grown in a greenhouse. Plants were tested for presence of SCYLV by tissue-blot immunoassay and reverse-transcription polymerase chain reaction after 5 to 6 months of growth. SCYLV genotypes BRA-PER, CUB, and REU were detected in 47, 62, and 39% of plants inoculated with these genotypes in Guadeloupe, respectively. SCYLV genotypes BRA-PER and REU and a mixed infection of genotypes BRA-PER and REU were detected in 56, 33, and 42% of plants inoculated with these genotypes in Réunion Island, respectively. Genotypes BRA-PER and CUB could be transmitted to all eight sugarcane cultivars, but genotype REU could never be transmitted to resistant sugarcane cvs. H78-4153 and H78-3567. SCYLV genotype REU was transmitted successfully to sugarcane cv. R570 in Guadeloupe, but not in Réunion Island. Genotypes BRA-PER and CUB induced yellow leaf symptoms in susceptible or highly susceptible sugarcane cultivars, whereas genotype REU induced very few symptoms. SCYLV was not found in several symptomatic plants, suggesting an association of disease with undetectable populations of the virus or a nonviral cause. This is the first report of variation in infection capacity and in virulence of SCYLV.


Additional keywords: Luteoviridae, Polerovirus

© 2007 The American Phytopathological Society