Yes off-course these microorganisms are really a serious risk for humans, we can take an example of outbreak of Shiga toxin-producing Escherichia coli O104:H4 in Germany. I have started a project on tracing such opportunistic pathogens in human food in India.

Thank you Praveen, I see a special risk in bacteria that have two virulence systems at the same time - one aganst plant and second - against animals (so far - insects). Fortunatelly, such pathogens so far affect a limited agricultural area.

But I have not found any report of Serratia being plant pathogen. Many researchers reported it as potential plant growth promoting bacteria. Can you share some more information on the phyto-pathogenicity of Serratia.

http://www.apsnet.org/publications/phytopathology/backissues/Documents/1982Articles/Phyto72n07_714.PDF

http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-09-11-0739-PDN

http://www2.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-VG-12.pdf

European Journal of Plant Pathology (2014) 138, 1-8

Annika Gillis, Margarita Rodríguez and María A. Santana (2014)

Serratia marcescens associated with bell pepper (Capsicum annuum L.) soft-rot disease under greenhouse conditions

Plant Disease (2012) 96, p. 761 (Sikora et al.)

E.J. Sikora, B.D. Bruton, A.C. Wayadande and J. Fletcher (2012)

First report of the cucurbit yellow vine disease caused by Serratia marcescens in watermelon and yellow squash in Alabama

Phytopathology (2003) 93, 1233-1239

J. Rascoe, M. Berg, U. Melcher, F.L. Mitchell, B.D. Bruton, S.D. Pair and J. Fletcher (2003)

Identification, phylogenetic analysis, and biological characterization of Serratia marcescens strains causing cucurbit yellow vine disease

Phytopathology (2003) 93, 1240-1246

Q. Zhang, R. Weyant, A.G. Steigerwalt, L.A. White, U. Melcher, B.D. Bruton, S.D. Pair, F.L. Mitchell and J. Fletcher (2003)

Genotyping of Serratia marcescens strains associated with cucurbit yellow vine disease by repetitive elements-based polymerase chain reaction and DNA-DNA hybridization

Plant Disease (2003) 87, 937-944

B.D. Bruton, F. Mitchell, J. Fletcher, S.D. Pair, A. Wayadande, U. Melcher, J. Brady, B. Bextine and T.W. Popham (2003)

Serratia marcescens, a phloem-colonizing, squash bug-transmitted bacterium: causal agent of cucurbit yellow vine disease

Plant Disease (2001) 85, 875-878

Blake Bextine, Astri Wayadande, B.D. Bruton, S.D. Pair, Forrest Mitchell and Jacqueline Fletcher (2001)

Effect of insect exclusion on the incidence of yellow vine disease and of the associated bacterium in squash

Plant Disease (1998) 82, 512-520

B.D. Bruton, J. Fletcher, S.D. Pair, M. Shaw and H. Sittertz-Bhatkar (1998)

Association of a phloem-limited bacterium with yellow vine disease in cucurbits

population dynamics/ epidemiology (1)

Plant Disease (2001) 85, p. 1031 (Wick et al.)

R.L. Wick, J. Lerner, S.D. Pair, J. Fletcher, U. Melcher, F. Mitchell and B.D. Bruton (2001)

Detection of cucurbit yellow vine disease in squash and pumpkin in Massachusetts

surveys/sampling/distribution (1)

Plant Disease (1999) 83, p. 587 (Bost et al.)

S.C. Bost, F.L. Mitchell, U. Melcher, S.D. Pair, J. Fletcher, A. Wayadande and B.D. Bruton (1999)

Yellow vine of watermelon and pumpkin in Tennessee

transmission/dispersal of plant diseases (5)

Annals of the Entomological Society of America (2005) 98, 770-774

Astri Wayadande, Benny Bruton, Jacqueline Fletcher, Sam Pair and Forrest Mitchell (2005)

Retention of cucurbit yellow vine disease bacterium Serratia marcescens through transstadial molt of vector Anasa tristis (Hemiptera: Coreidae)

Journal of Economic Entomology (2004) 97, 74-78

S.D. Pair, B.D. Bruton, F. Mitchell, J. Fletcher, A. Wayadande and U. Melcher (2004)

Overwintering squash bugs harbor and transmit the causal agent of cucurbit yellow vine disease

Plant Disease (2003) 87, 937-944

B.D. Bruton, F. Mitchell, J. Fletcher, S.D. Pair, A. Wayadande, U. Melcher, J. Brady, B. Bextine and T.W. Popham (2003)

Serratia marcescens, a phloem-colonizing, squash bug-transmitted bacterium: causal agent of cucurbit yellow vine disease

Southwestern Entomologist (2003) 28, p. 63 (Bextine et al.)

Blake R. Bextine, Astri Wayadande, B.D. Bruton, S.D. Pair, Forrest Mitchell and Jacqueline Fletcher (2003)

Artificial feeding system for the squash bug, Anasa tristis (De Geer) (Heteroptera: Coreidae)

Plant Disease (2001) 85, 875-878

Blake Bextine, Astri Wayadande, B.D. Bruton, S.D. Pair, Forrest Mitchell and Jacqueline Fletcher (2001)

Effect of insect exclusion on the incidence of yellow vine disease and of the associated bacterium in squash

molecular biology - genes (2)

Applied and Environmental Microbiology (2005) 71, 7716-7723

Q. Zhang, U. Melcher, L. Zhou, F.Z. Najar, B.A. Roe and J. Fletcher (2005)

Genomic comparison of plant pathogenic and nonpathogenic Serratia marcescens strains by suppressive subtractive hybridization

Phytopathology (1996) 86, S75-S76

F.J. Avila, B.D. Bruton, J.L. Sherwood, J. Fletcher and S.D. Pair (1996)

Amplification of DNA from yellow vine affected watermelon by polymerase chain reaction

Hi Alex, since it seems that you are familiar with literature on serratia as a plant pathogen, is there (in any of these publications) standard protocol which could be used to test serratia strains virulence in plants (like using squash leaves?). I have only used insect models for testing serratia virulence and it would be super neat to be able to test also same kind of ideas in plants

Hi Tarmo,

The methods used for plant pathogenic bacteria are pretty the same for all species: 1) indicator plant leaf infiltration for HR (tobacco, pelargonium, plectranthus, etc.);

2) germinating seeds inoculation (mainly for for toxins)

3) seedlings inoculation via excised cotyledons for systemic infection (just good for Serratia) or cut roots

4) stem or petiole injection, clipping, pinning, cutting leaves for xylem and mesophyll pathogens (canker, back rot).

5) leaf infiltration or spraying with or without wounding for leaf spot pathogen 

6) most natural - inoculation in dew and guttation droplets.

7) inoculation with vector

8) some are using inoculation of detached leaves or stems, but it has many limitations.

As I said before, some Serratia are pathogenic for sunflower, and some - for onion and potato plants

Thanks Alex for the information, maybe I try some of the plants and methods in near future.