A mobile genetic element in Serratia marcescens, a causative agent of onion disease

Abstract

Aim. To screen mobile genetic elements (MGE) in the bacterium which caused decay of field-grown onion bulb and to study an integron and gene cassettes associated. Methods. Polymerase chain reaction (PCR) and PCR products sequencing were used for both the bacterium and MGE identification. Terminally-labeled Restriction Fragment Length Polymorphism (TRFLP) analysis was performed for detection of any bacterium in the onion bulb tissue. Results. The bacterium, which caused field-grown onion decay, was identified by nucleotide sequence analysis of the 16S rRNA genes to be S. marcescens known as phytopathogen. However, this isolate did not respond to specific primers designed for pathogenic strains. Inoculation of onion (Allium cepa L.), Arabidopsis thaliana (L.) Heyhn, and lettuce (Lactuca sativa) seeds resulted in biomass promotion of symptomless plants. PCR revealed the presence of a class 1 integron in S. marcescens IMBG291 which represents the first isolation of this integron in phytopathogenic Serratia species. The gene cassettes harbored by the integron have been represented with the promoterless genes encoded formimino-glutamate deiminase and ascorbate-specific phosphotransferase system enzyme IIC, and with additional three senseless sequences flanked by a 59-bp element. Conclusion. S. marcescens IMBG291 exhibited plant growth promotion or pathogenicity, depending on the environmental situation, due to horizontally acquired new gene cassettes located in the integron

Nematicidal Bacteria Associated to Pinewood Nematode Produce Extracellular Proteases

“…The diversity of roles that can be assumed by the same bacterial species, as Serratia marcescens , goes from plant grow promoting to phytopathogen through the acquisition of genetic mobile elements or environmental stimuli [42,43]. Understanding all the involved factors is important in order to develop strategies to control B. xylophilus dispersions.…”

Understanding pine wilt disease: roles of the pine endophytic bacteria and of the bacteria carried by the disease‐causing pinewood nematode

“…Possibly, the initial comparison between genomes (draft or completed) will elucidate genetic differences between genomes reflecting the diversity of assumed roles by strains of the same bacterial species from different environments. In case of Serratia marcescens , a second example, this reaches from being a plant growth promoter (Dong, Gu, Guo, Xun, & Liu, ), specially under plant stress, to acting as a phytopathogen through the acquisition of genetic mobile elements with an integron harboring genes that take part in the histidine metabolism (Ovcharenko et al., ) or responding to environmental stimuli (Zhang et al., ).…”

The enemy within: phloem‐limited pathogens

“…Mobile genetic elements probably contributed to the acquisition of the aforementioned genes, a hypothesis supported by the over‐representation of a transposase in CCS (Zhang et al ., ). In addition, an onion‐infecting S. marcescens strain contains a potentially pathogenesis‐promoting mobile genetic element (Ovcharenko et al ., ). These findings suggest that the versatility of S. marcescens strains is a result of mobile genetic elements, and that CCS could have specialized in this fashion.…”

“…It is unclear where in the vector CCS is maintained, and research has shown CCS can overwinter in dormant A. tristis (Pair et al, 2004;Purcell and Finlay, 1979;Wayadande et al, 2005). Other S. marcescens strains are also plant pathogens, but are not insect vectored or phloem limited (Gillis et al, 2014;Ovcharenko et al, 2010;Wang et al, 2014). These strains, and the generalist nature of A. tristis, raise the intriguing possibility that CCS is an example in which a pathogen first infected plants before evolving to associate with an insect vector and becoming phloem limited (plant-first evolution) (Nadarasah and Stavrinides, 2011).…”