Archivio Journal of Plant Pathology

Abstract:

During a survey (2002-2012) on olive groves in Apulia (southern Italy), many trees of cv. Coratina were found, exhibiting cankers on twigs and branch dieback. Phomopsis spp. were isolated (15-65%) from symptomatic twigs. Genomic DNA was extracted from 43 fungal isolates. The ITS gene region was amplified with primers ITS1/ITS4 (White et al., 1990) and sequenced. Blast analysis of ITS sequences of 38 isolates showed 100% similarity with Diaporthe neotheicola A.J.L. Phillips et J.M. Santos (GenBank accession No. EU814480) whereas five isolates had 100% similarity with D. ambigua Nitschke (EU814478). ITS sequences of D. ambigua and D. neotheicola isolates from olive were deposited in GenBank under the accession Nos. HM575419, HM575420 and HM575421, HM575422, respectively. Microscopic features of D. neotheicola from Apulian olive trees and matched those described by Phillips and Santos (2009) while features of D. ambigua were identical with those previously described for this species. Pathogenicity tests were conducted in May 2012 and 2013 using two isolates/species on 1-year-old twigs of cv. Coratina by inoculating them with each isolate or with sterile agar (controls). Symptoms were observed after 90 days and Diaporthe species were re-isolated thus, fulfilling Koch’s postulates. Control plants were symptomless. The two species of Phomopsis from olive could be a potential inoculum source for grapevines. Indeed, Mostert et al. (2001) reported D. ambigua and Phomopsis sp. 1, the latter referred to as D. neotheicola, from Vitis vinifera. To our knowledge, this is the first report of D. neotheicola and D. ambigua on olive.