Enterobacter mori Causing Leaf Spot and Soft Rot in Three New Ornamental Hosts

Abstract

Leaf spot and soft rot of ornamental plants were observed in the Alborz and Markazi provinces during the summer and autumn of 2022. Eighteen samples were collected from symptomatic ornamental plants in Karaj and Arak cities. Necrotic leaf spots surrounded by a broad yellow halo were observed in the affected pothos (Epipremnum aureum) and compact dragon (Dracaena compacta) plants. On the severely affected, leaves of compact dragon with a yellow margin were observed. Soft rot symptoms which turned dark brown areas were observed on the diseased jade plants (Crassula ovata). The colonies of bacterial strains were cream-coloured, round, convex, smooth and with entire margins on nutrient agar. In the pathogenicity of 35 recovered strains, the five strains isolated from pothos caused water-soaking 2 days after inoculation, which finally turned into necrotic lesions surrounded by chlorotic halos. Eight strains isolated from compact dragon produced necrotic spots on the inoculated plants. Five strains originated from jade plants induced soft rot 4–5 days post-inoculation. All 18 pathogenic strains were negative in Gram and oxidase reactions. The gyrB and infB gene sequences of eight representative strains were partially amplified and sequenced. In the maximum-likelihood phylogenetic tree created based on the concatenated sequences of gyrB and infB genes, the strains clustered with Enterobacter mori LMG 25706^T supported with bootstrap value of 100%. To the best of our knowledge, this is the first report of pothos and compact dragon leaf spot and jade plant soft rot caused by E. mori.