Brown spot caused by Sphingomonas sp. on yellow Spanish melon fruits in Spain*

Abstract

Brown fruit spot symptoms were observed on yellow Spanish melons (Cucumis melo var. inodorus) grown in greenhouses at Almeria in Spain. Nonsporing, motile, rod-shaped bacteria were isolated from diseased fruits, which on nutrient agar produced small yellow colonies. Two bacterial isolates, used for further investigations, were pathogenic on fruits but not on cotyledons of Spanish melon plants. They provoked disease symptoms similar to those observed in the greenhouse. Both isolates were Gram-negative, catalase-positive, weakly oxidase-positive and phenylalanine deaminase-negative. They hydrolysed esculin but not gelatin and they utilized glucose oxidatively. Fatty acid analysis revealed that both isolates belong to the genus Sphingomonas. In addition, 16S rDNA sequence analysis, performed on one isolate, demonstrated that it had a significant sequence similarity (more than 98%) with Sphingomonas pruni and Sphingomonas mali, nonphytopathogenic bacteria isolated from plants. Although enterobacterial repetitive intergenic consensus PCR and repetitive extragenic palindromic PCR seem to indicate that the Sphingomonas isolates from Spanish melon fruits may belong to a new species, DNA±DNA hydridization analysis is necessary to verify this hypothesis.

Sphingomonas melonis sp. nov., a novel pathogen that causes brown spots on yellow Spanish melon fruits

“…inodorus Naud.) cultivated in greenhouses in Almeria, Spain (Buonaurio et al, 2001). When yellow Spanish melon fruits and leaves were inoculated with the bacterium, only fruits showed disease symptoms.…”

“…When yellow Spanish melon fruits and leaves were inoculated with the bacterium, only fruits showed disease symptoms. 16S rDNA sequence analysis performed on one bacterial isolate revealed that it was phylogenetically closely related to Sphingomonas mali, Sphingomonas pruni and Sphingomonas asaccharolytica (Buonaurio et al, 2001).…”

“…A phytopathogenic Sphingomonas species has been reported to cause brown spot on yellow Spanish melon (Cucumis melo var. inodorus) fruit (Buonaurio et al, 2001). Since it has been reported that a large population of Sphingomonas species grows on the surface of many plants (Kim et al, 1998), it could be hypothesized that this Sphingomonas species grows as an epiphyte on melon fruit and that this capacity increases the likelihood of fruit infection.…”

Bark from avocado trees of different geographic locations have consistent microbial communities

“…This genus has both phytopahtogenic (Buonaurio et al 2001;Deldavleh et al 2013;Kini et al 2017) and plant-beneficial strains, which provide protection against pathogens (Berg and Ballin, 1994;Innerebner et al 2011) and abiotic stress (Halo et al 2015;Asaf et al 2017). These complex relationships of Sphingomonas with plants are an interesting case for future studies on the evolution of plant-microorganism interactions.…”

First report of Sphingomonas sp. causing bacterial leaf blight of rice in Benin, Burkina Faso, The Gambia, Ivory Coast, Mali, Nigeria, Tanzania and Togo

“…Sphingomonas species have frequently been isolated from rice seed (Midha et al , 2016) and have been found on leaves of 26 plant species of 11 families but few are recorded as plant pathogens. Sphingomonas melonis , is the causal agent of a brown spot disease on fruits of Cucumis melo (Buonaurio et al , 2001) and Sphingomonas sp. causes bacterial leaf blight of Paliuris spina‐christi (Deldavleh et al , 2013), The present report seems to be the third case of a plant disease caused by a member of this genus.…”