Testing for Pseudomonas syringae pv. atrofaciens and Xanthomonas campestris pathovars on cereals in Italy

During recent years, recurrent attacks of basal glume rot/leaf blight attributed to Pseudomonas syringae pv. atrofaciens have been observed on cultivars of durum wheat grown in the Po valley (IT). The main aim of this study was to test for this pathogen and Xanthomonas campestris pathovars in commercial seed lots of cereals produced in different regions of Italy, as well as in symptomatic plants collected in the field. None of the analyses led to the detection of xanthomonads. In testing for P.s. atrofaciens, representative bacterial isolates were selected and characterized; this was done by combining conventional identification tests and computerized densitometric analysis of electrophoretic patterns of cell proteins obtained using the SDS‐PAGE technique. P.s. atrofaciens was detected in seed samples (barley, wheat and durum wheat) and symptomatic plants (durum wheat) grown in northern and central Italy. The possible pathogenic role of other unrelated fluorescent pseudomonads in this interaction was also examined. Difficulties in discriminating pvs syringae and atrofaciens of P. syringae are discussed and the uncertain taxonomic relationship between these two pathovars is emphasized. Copyright © 1995, Wiley Blackwell. All rights reserved