SUMMARY Several strains of Pseudomonas savastanoi pv. savas- tanoi, causal agent of galls or knots on leaves, twigs, and stems of various plant species, were isolated from in- fected olive (Olea sp.), oleander (Nerium oleander), jas- mine (Jasminium officinale), fontanesia (Fontanesia phillyreoides) and myrtle (Myrtus communis) plants growing in Adana, Antalya, Bursa, Canakkale, Hatay, Izmir, Mersin, Mugla, Samsun and Tekirdag provinces of Turkey. Among the strains initially tested, 33 of them from different hosts were selected for further analyses. The strains were Gram-, oxidase-, pectolytic activity-, levan-, and arginine dihydrolase negative, showed fluo- rescence on King’s B and PVF-1 media and induced hy- persensitive reaction on tobacco leaves. Three products 464 bp, 684 bp and 1064 bp in size were amplified by PCR. Fatty acid methyl ester profiles confirmed the identity of tested strains as P. savastanoi pv. savastanoi. Based on cluster analysis of fatty acids, the strains were divided into two different groups. No correlation was found, however, between host plant and geographical origin of the strains under study. Olive, oleander, jas- mine, fontanesia and myrtle plants were used to deter- mine pathogenicity of the strains, which were generally most virulent when inoculated to the original host. This is the first detailed study showing that P. savastanoi pv. savastanoi can cause knot disease on the new oleaceous host Fontanesia phillyreoides. Key words: Pseudomoanas savastanoi, olive, oleander, jasmine, fontanesia, myrtle, FAME, PCR. INTRODUCTION Pseudomonas savastanoi pv. savastanoi is a pathogenic bacterium inducing galls or knots on stem, twigs, and leaves of several host plants belonging to the family Oleaceae and the related family Apocynaceae (Janse, Corresponding author: M. Mirik Fax: +90 282 2933476 E-mail: mmirik@nku.edu.tr 1981). According to current classification, three different pathovars of P. savastanoi denoted savastanoi, nerii and fraxini, elicit hyperplastic growth formations (galls or knots) on young stems and branches of olive (Olea spp.), oleander (Nerium oleander), and ash (Fraxinus excelsior), respectively (Young et al., 1996). Earlier studies have re- ported the occurrence of this disease on olive (Smith, 1908; Young et al., 1978), oleander (Wilson, 1965); jas- mine [Jasminium officinale (Janse, 1981)], ash [Fraxinus excelsior (Janse, 1981)], privet [Ligustrum japonicum (Bottalico and Ercolani, 1971)], Forsythia and Phyllyirea (Iacobellis et al., 1998; Alvarez et al., 1998). The presence of bacterial knot in Turkey was ob- served on olives growing in the Aegean (Azeri, 1993; Tatli and Benlioglu, 2004) and western Mediterranean (Basim and Ersoy, 2000) regions of the country and on oleander in Sanliurfa (south-eastern Anatolia) (Kavak and Ustun, 2009). Hyperplasia of affected tissues that evolves into clearly visible knots is induced by in- dolacetic acid (IAA) and cytokinins produced by the pathogen (Smidt and Kosuge, 1978; Surico et al., 1985; Iacobellis et al., 1994). Bacterial strains from different host plants can be distinguished on the account of dif- ferential characteristics related to pathogenicity, bio- chemical features, genome structure and production of phytohormones (Surico et al., 1985; Surico and Iacobel- lis, 1992). Janse (1991) divided P. savastanoi pv. savas- tanoi strains into three homogenous groups, based on the fatty acids profiles and host plant interactions. The objective of the present study was to character- ize P. savastanoi pv. savastanoi strains from olive, olean- der, jasmine, fontanesia (a hitherto unknown host of the bacterium) and myrtle plants growing in the Turkish provinces of Adana, Antalya, Bursa, Canakkale, Hatay, Izmir, Mersin, Mugla, Samsun and Tekirdag on the ba- sis of morphological, physiological and biochemical tests, hypersensitive reaction (HR) on tobacco, patho- genicity tests, fatty acid methyl ester (FAME) profiles, and genetic fingerprinting. MATERIALS AND METHODS Isolation. Knotted samples form olive, oleander, jas- Journal of Plant Pathology (2011), 93 (2), 263-270 Edizioni ETS Pisa, 2011 263 CHARACTERIZATION OF PSEUDOMONAS SAVASTANOI pv. SAVASTANOI STRAINS ISOLATED FROM SEVERAL HOST PLANTS IN TURKEY AND REPORT OF FONTANESIA AS A NEW HOST M. Mirik 1 , Y. Aysan 2 and F. Sahin 3 1 Namik Kemal University, Faculty of Agriculture, Department of Plant Protection, Tekirdag 59030, Turkey 2 Cukurova University, Faculty of Agriculture, Department of Plant Protection, Adana 01130, Turkey 3 Yeditepe University, Faculty of Engineering and Architecture, Department of Genetics and Bioengineering, Istanbul 34755, Turkey