SUMMARY

Fluorescent colonies were obtained from surface-sterilized twigs of healthy wild trees of Corylus avellana L. growing in central Italy. LOPAT, biochemical and pathogenicity tests, and 16S rDNA gene sequencing in-dicated that one endophytic isolate belonged to the Pseudomonas syringae species complex. This isolate in-cited hazelnut twig dieback only when inoculated at 1-2 × 105 CFU/ml per leaf scar. Lower doses did not induce symptoms. The isolate also caused necrosis in pear and lilac twigs, lemon fruits and bean pods. To our knowl-edge, this is the first report of an endophytic P. syringae strain obtained from wild C. avellana trees. Key words: Hazelnut, pseudomonads, endophytic bacteria, 16S rDNA, gene sequencing Endophytic bacteria are generally considered as harmless to the host plant and can be isolated from sur-face-sterilized plant tissue or from the inner parts of the plant (Hallman et al., 1997). Studies aimed at identify-ing endophytic bacteria from crops and wild plants have shown that apart from saprophytic, mutualistic or bene-ficial species, plant pathogens were also found in some cases. Examples are Pseudomonas viridiflava in pea stems (Elvira-Recuenco and Van Vuurde, 2000), Curto-bacterium flaccumfaciens and Clavibacter michiganensis in prairie plants (Zinniel et al., 2002), Curtobacterium flaccumfaciens and Xanthomonas campestris in orange and tangerine (Araujo et al., 2002), Burkholderia gladioli, and Curtobacterium flaccumfaciens pathovars flaccumfaciens, oort and poinsettiae in coffee seeds (Vega et al., 2005). However, such studies did not assess the pathogenicity, and therefore the exact identity, of the endophytic strains towards the host plants from which they were originally isolated. Corylus avellana L. (hazelnut), is widely cultivated i