First Report of Pseudomonas Viridiflava Causing Cabbage Bacterial Leaf Spot in Turkey

Abstract

In the autumn of 2016, white head cabbage (Brassica oleracea var. capitata f. alba) showing circular to irregular lesions 2-3 mm in size surrounded by a yellow halo and necrotic areas on the leaves, were observed in the Samsun province of Turkey. Extract from symptomatic tissue macerated in plastic bags (Bioreba AG, Switzerland), plated on King’s medium B (King et al., 1954) and incubated at 26°C for 48 h yielded colonies with the same LOPAT profile of Pseudomonas viridiflava strain M66 from tomato. They were levan-, oxidase-, arginine-negative, caused hypersensitive reactions on tobacco leaves (Nicotiana tabacum cv. Xanthi) and macerated potato slices. Molecular characterization using ERIC-PCR (Rademaker et al., 1998) yielded the same band pattern for strains BT5X and M66. Blastn analysis of a 1400 bp 16S rDNA and a 835 bp gyrB gene sequence (GenBank accession Nos. KY769809, MF314821) showed 99% and 100% similarity to the sequences of the type strain ATCC13223T =CFBP 2107 (NR_114482- HM190239) of Ps. viridiflava deposited in GenBank. Multilocus sequence analysis (MLSA) produced by maximum likelihood method using concatenated sequences of 16S rDNA and gyrB allowed clustering of our strain in the same clade together with the type strain ATCC13223T and other representive P. viridiflava strains retrieved from GenBank. Cabbage plants (cv. Beyaz Bursa) were spray-inoculated with a suspension of 108 CFU ml-1 of an overnight culture grown in Luria-Bertani broth reacted six days post inoculation with spots similar to those observed in the field. Reisolated colonies were fluorescent under UV light and had the same morphology on King’s medium B as the original culture and positive strain M66. To our knowledge, this is the first report of P. viridiflava causing a leaf spot disease of head cabbage in Turkey. © 2017, Edizioni ETS. All rights reserved.