Joaquin Cañizares,2 and
Miguel A. Aranda1
1Departamento de Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura (CEBAS)–CSIC, apdo. correos 164, 30100 Espinardo (Murcia), Spain; 2Instituto de Conservación y Mejora de la Agrodiversidad Valenciana (COMAV)–UPV, Camino de Vera s/n, 46022 Valencia, Spain
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Accepted 12 September 2011.
Resistance to Watermelon mosaic virus (WMV) in melon (Cucumis melo L.) accession TGR-1551 is characterized by a significant reduction in virus titer, and is inherited as a recessive, loss-of-susceptibility allele. We measured virus RNA accumulation in TGR-1551 plants and a susceptible control (‘Tendral’) by real-time quantitative polymerase chain reaction, and also profiled the expression of 17,443 unigenes represented on a melon microarray over a 15-day time course. The virus accumulated to higher levels in cotyledons of the resistant variety up to 9 days postinoculation (dpi) but, thereafter, levels increased in the susceptible variety while those in the resistant variety declined. Microarray experiments looking at the early response to infection (1 and 3 dpi), as well as responses after 7 and 15 dpi, revealed more profound transcriptomic changes in resistant plants than susceptible ones. The gene expression profiles revealed deep and extensive transcriptome remodeling in TGR-1551 plants, often involving genes with pathogen response functions. Overall, our data suggested that resistance to WMV in TGR-1551 melon plants is associated with a defense response, which contrasts with the recessive nature of the resistance trait.
© 2012 The American Phytopathological Society