Scientia Horticulturae 144 (2012) 81–86 Contents lists available at SciVerse ScienceDirect Scientia Horticulturae journa l h o me page: www.elsevier.com/locate/scihorti Sensitivity of peach cultivars against a Dideron isolate of Plum pox virus Manuel Rubio a,∗ , Pedro Martínez-Gómez a , Jesús García-Brunton b , Thierry Pascal c , Ana García-Ibarra a , Federico Dicenta a a Department of Plant Breeding, CEBAS-CSIC, PO Box 164, E-30100 Espinardo, Murcia, Spain b Department of Horticulture, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), E-30150 La Alberca, Murcia, Spain c Unité de Recherche en Génétique et Amélioration des Fruits et Légumes,GAFL. INRA-Avignon, Domaine Saint-Maurice, BP 94/84143 Monfavet, France a r t i c l e i n f o Article history: Received 17 May 2012 Received in revised form 26 June 2012 Accepted 27 June 2012 Keywords: Breeding PPV Prunus persica Disease resistance Sharka a b s t r a c t Sharka disease, caused by Plum pox virus (PPV), is one of the most significant limiting factors for Prunus production worldwide, and the cultivation of resistant cultivars is the only definitive solution to this problem. In this study, 40 cultivated peach cultivars with different origins, chill requirements and fruit type were evaluated against a PPV Dideron-type isolate in controlled conditions in greenhouse for three evaluation cycles. Cultivars were grafted onto PPV infected ‘GF305 ′ rootstocks and, in each cycle, the presence of symptoms on leaves was scored and ELISA and RT-PCR was applied to check the presence of PPV on rootstocks and cultivars. The results showed the resistance of ‘Catherine’ to this strain, for this cultivar never showed sharka symptoms and was ELISA and RT-PCR negative. Some cultivars without symptoms but ELISA or PCR positive were tolerant to PPV. Most cultivars were sensitive, and showed symptoms of sharka or were ELISA or RT-PCR positive. In these cultivars, different degrees of symptom expression among the three cycles and between replications of each cultivar were observed. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The economic cost of Plum pox virus (PPV, sharka) in Prunus species has been estimated at around 10,000 million euros over the last 30 years (Cambra et al., 2006). Among the different Prunus species sensitive to this disease, peach [Prunus persica (L.) Batsch] is one of the most affected (Van Oosten, 1975). In sensitive Prunus, PPV produces symptoms on leaves, flowers and fruits, which become unmarketable, and also affects vegetative growth and increases fruit drop (Németh, 1994; Milosevic et al., 2010). In countries where PPV is widespread, the cultivation of new resistant cultivars is the only alternative for maintaining stone fruit production (Németh, 1994). Public and private peach breeders release a significant number of new cultivars each year. Between 1991 and 2001, close to 1200 new cultivars were released worldwide (Sansavini et al., 2006). PPV resistance is a desirable trait in some of these peach breeding programs (Gabova, 1994; Gass et al., 1996; Sansavini et al., 2006), although most peach cultivars evaluated so far have been reported as sensitive. Escalettes et al. (1998) evaluated 250 peach clones, and only the clones S2844 (from Russel Red) and S2873 (from Early Double Red) were resistant against Marcus (PPV-M) and Dideron ∗ Corresponding author. Tel.: +34 968 39 62 00; fax: +34 968 39 62 13. E-mail addresses: mrubio@cebas.csic.es (M. Rubio), jesus.garcia2@carm.es (J. García-Brunton), tpascal@avignon.inra.fr (T. Pascal). (PPV-D) PPV isolates, although Pascal et al. (2002) later showed the sensitivity of these cultivars to PPV-M. However, despite this predominant feature, important variability exists within peach species, ranging from very sensitive to tolerant or resistant culti- vars (Gabova, 1994; Toma et al., 1998; Polák et al., 2003; Tsiporidis et al., 2005; Casati et al., 2010). Furthermore, in Prunus and mainly in peach, PPV-M isolates produce stronger symptoms and spread faster than PPV-D isolates (Quiot et al., 1995; Dallot et al., 1998; Candresse and Cambra, 2006). PPV-M was detected in Spain and eradicated (Cambra et al., 2004), and, to date, no official evidence of these isolates has been reported since in this country. In this study, the resistance of 40 peach cultivars to a PPV-D iso- late was evaluated in controlled greenhouse conditions by grafting these cultivars onto inoculated ‘GF305 ′ peach rootstocks. 2. Materials and methods 2.1. Plant material Forty cultivated peach cultivars of different origins were evalu- ated. The cultivars (including nectarines, clingstone and freestone peaches) have different chill requirements and come from Brazil, France, Italy, Spain and USA. The pedigree of most of these cultivars is unknown, probably because they were released by private breed- ers (Table 1). The selected cultivars were grafted onto ‘GF305 ′ peach seedling rootstocks, described as very sensitive to PPV (Bernhard 0304-4238/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scienta.2012.06.038