Archivio Journal of Plant Pathology

Abstract:

Apple is known to host many viruses and mixed infection by these viruses can induce significant yield reductions. Apple chlorotic leaf spot virus (ACLSV), apple mosaic virus (ApMV) and apple stem pitting virus (ASPV) have been reported previously in Tunisia (Mahfoudhi et al., 2013). Apple stem grooving virus (ASGV), the type member of the genus Capillovirus, family Betaflexiviridae, is widely distributed in apple trees and has been associated with tree decline and graft union necrosis in sensitive combinations of scion and rootstock (Yanase et al., 1990). To investigate the presence of ASGV in Tunisian apple orchards, a survey was conducted in the main apple growing regions and leaf samples were randomly collected in spring 2016 from 90 trees representing four important cultivars (Golden, Lorka, Richared, Anna). Total nucleic acids were extracted from leaf veins and purified according to Foissac et al. (2001). All samples were tested by RT-PCR for the presence of ASGV using specific primers (Menzel et al., 2002) for the amplification of a 273 bp fragment from the coat protein coding region. Results showed that 31% of the tested samples were infected by ASGV. The infection rate ranged from 25% (cv. Richared) to 50% (cv. Golden). To confirm the identity of this virus, two isolates of ASGV were sequenced and sequences were compared to those available in GenBank. The nucleotide sequence of Tunisian ASGV isolates R161 (LT882718) and G171 (LT882719) showed identities of 96 and 99% with ASGV iso3_IN/GARD (LT574875), respectively. To our knowledge this is the first report of ASGV in Tunisian apple orchards.