Leaf spot disease on Philodendron scandens, Ficus carica and Actinidia deliciosa caused by Pseudomonas syringae pv. syringae in Serbia

During the spring of 2014 and 2015, a leaf spot disease was observed on heart-leaf philodendron (Philodendron scandens Koch & Sello) plants grown in a several house gardens near city of Jagodina, Moravički region of Serbia. Diseased leaves were covered with watersoaked leaf spots with surrounded by yellow halos. Based on biochemical and molecular tests Pseudomonas syringae pv. syringae was identified as causing agent of bacterial leaf spot of heart-leaf philodendron and is in humid season accountable for appearence of disease. The genetic diversity within this pathogen isolated from different hosts in central Serbia, was studied to obtain insights into disease etiology. Therefore, kiwi fruit and fig tree leaves, with disease symptoms that were similar to those observed on heart-leaf philodendron plants, were collected and bacteria were isolated on NAS medium. Isolates were identified as P. syringae pv. syringae by detection of syrB gene, biochemical, pathogenicity tests and sequencing of gyrB gene. In cross inoculation tests on potted host plants, each strain induced leaf spot symptoms on heart-leaf philodendron and fig tree leaves, apart of the host of origin, and no significant symptoms in kiwi fruit leaves. Genomic profiles generated with rep-PCR analysis revealed that all strains originated from diseased heart-leaf philodendron, kiwi fruit and fig tree leaves had similiar DNA fingerprints. Overall, the data demonstrate P. syringae pv. syringae as a causing agent of leaf spot disease of heart-leaf philodendron and fig tree in Moravički region of Serbia. This research is the first study that identified P. syringae pv. syringae associated with leaf spot disease on P. scandens, and also a starting point for investigation of the epidemiology of leaf spot disease on fruit trees that could be infected by the same bacterial strains.