Progress 12/01/08 to 11/30/13
Outputs
Target Audience: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit and bacterial pathogens as well as the microbiology research community that works on bacterial pathogenesis. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? The results have been disseminated to the scientific community through refereed publications. Results have been disseminated to the grower community through presentations at grower meetings, Youtube educational videos, and through newsletter articles available on the Michigan State University Extension News website. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We collected a total of 300 presumptive Gram-negative bacterial isolates in 2013 from leaf and soil samples from 8 commercial orchards and 1 research orchard in Michigan. These isolates were capable of growth on King's B medium amended with 250 ppm kasugamycin. The bacteria were screened for resistance to other aminoglycoside antibiotics gentamicin and streptomycin and to the antibiotics tetracycline, ampicillin, and ceftoxamine. Our results did not show that kasugamycin resistance is associated with cross resistance to other aminoglycoside antibiotics or to the other antibiotics screened. Our surveys in 2013 indicated that streptomycin resistance in the fire blight pathogen Erwinia amylovora is spreading very slowly among commercial apple orchards in southwest Michigan and is present in a wider range of apple orchards in northwest Michigan compared to 2012. Genetic analyses continue to show that resistance is associated with two strain types that appear to be spreading between orchards. We determined that biofilm formation in E. amylovora is regulated by the Hfq small RNA chaperone protein. An E. amylovora hfq had a hyper-attachment phenotype with reduced aggregation between cells. Thus, the overall phenotype was a reduction in biofilm formation. Hfq also controlled production of the major exopolysaccharide amylovoran, a component of biofilms. We also determined that hfq regulated cell motility, another key virulence determinant in E. amylovora. We examined the role of the second messenger molecule cyclic di-GMP in E. amylovora virulence and determined that the organism produces 5 active diguanylate cyclases (enzymes that synthesize cyclic di-GMP). We showed that c-di-GMP positively regulates secretion of the main exopolysaccharide in E. amylovora, amylovoran, leading to increased biofilm formation, and negatively regulates flagellar swimming motility. Although biofilm formation is important for the colonization of plant xylem tissues and the development of systemic infections, deletion of the two biofilm-promoting DGCs increased tissue necrosis in an immature pear infection assay and apple shoot infection model. This suggests that c-di-GMP negatively regulates virulence.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Zeng, Q., R.R. McNally, and G.W. Sundin. 2013. Global RNA chaperone Hfq and regulatory small RNAs control virulence in the fire blight pathogen Erwinia amylovora. Journal of Bacteriology 195:1706-1717.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Edmunds, A.C., L.F. Castiblanco, G.W. Sundin, and C.M. Waters. 2013. Cyclic di-GMP modulates the disease progression of Erwinia amylovora. Journal of Bacteriology 195:2155-2165.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Vogt, I., T. W�hner, K. Richter, H. Flachowsky, G.W. Sundin, A. Wensing, E.A. Savory, K. Geider, B. Day, M.-V. Hanke, and A. Peil. 2013. Gene-for-gene relationship in the host-pathogen system Malus x robusta 5 Erwinia amylovora. New Phytologist 197:1262-1275.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management, and our research focused on fire blight in 2009. ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. This work confirmed the efficacy of two formulations of the experimental antibiotic kasugamycin for blossom blight control under Michigan conditions. Levels of control were similar to those observed with streptomycin, the industry standard. Additional experimental treatments using bacterial and yeast antagnosit biological control agents resulted in increased control compared to nontreated trees; however, these materials were not as effective as kasugamycin or streptomycin. We continue to pursue several lines of basic research aimed at fully understanding the interaction of the fire blight pathogen Erwinia amylovora with its apple host at the molecular level. We characterized the role of the second messenger molecule cyclic di-GMP in affecting virulence traits such as motility and biofilm formation. Two genes were identified that enabled E. amylovora to produce c-di-GMP; overepxression of these genes resulted in increased amylovoran exopolysaccarhide production and biofilm formation. We also analyzed the role of small RNA molecules in regulating virulence traits. We determined that the Hfq small RNA chaperone was an important virulence regulator. A deletion mutant of hfq in E. amylovora Ea1189 was significantly reduced in virulence and in amylovoran exopolysaccharide production, biofilm formation, motility, and the type III secretion system (T3SS). We also characterized the clustered regularly interspaced short palindromic repeats (CRISPRs) system in E. amylovora, used comaprative sequence analysis of CRISPR loci to differentiate a worldwide collection of strains, and showed that CRISPRs could be used for strain tracking of genotypes at a local level. Results are disseminated to the research community via refereed publications in journals and through refereed research reports published in Plant Disease Management Reports. Results are disseminated to the grower community through presentations given at grower meetings and field days and through newsletter articles published in the Michigan State University MSUE News website and in trade magazines. EVENTS: Research presentations at scientific meetings included two presentations at the American Phytopathological Society North Central Division meeting, six presentations at the American Phytopathological Society national meeting, and two presentations at the Great Lakes Fruit Workers Conference. A total of 9 grower training sessions and 4 sessions targeting industry fruit extension workers were given on fire blight disease control and 2 training sessions were given on bacterial spot and bacterial canker control. PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Luisa Castiblanco - graduate student - designed and performed research related to the role of cyclic di-GMP in E. amylovora virulence. Ryan McNally - graduate student - designed and performed research related to the role of Hfq in E. amylovora virulence. Quan Zeng - postdoctoral research associate -- designed and performed research related to the role of Hfq and small RNAs in E. amylovora virulence. TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we found that the experimental antibiotic material kasugamycin was efficacious for fire blight control under field conditions. We determined that regulatory moleculaes such as cyclic di-GMP and small RNAs were important virulence regulators in Erwinia amylovora. CHANGE IN ACTIONS: Experimental antibiotics are examined for fire blight efficacy due to the occurrence of streptomycin resistance in orchard populations of E. amylovora in Michigan. Dissemination of this knowledge to Michigan apple growers has enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures. Our work has provided the necessary data for the state of Michigan to submit emergency requests to the Environmental Protection Agency for Section 18 exemptions such that Michigan growers can utilize kasugamycin for fire blight control.
Publications
- McGhee, G.C., G.W. Sundin, and G.R. Ehret. 2012. Applications of Actigard as a drench and foliar spray in the control of fire blight, 2011. Plant Dis. Mgmt. Rep. 6:PF011.
- Sundin, G.W., G.R. Ehret, T.T. Forton, and G.C. McGhee. 2012. Fire blight control on Jonathan apple with Kasumin in 2011. Plant Dis. Mgmt. Rep. 6:PF004.
- Sundin, G.W., G.R. Ehret, G.C. McGhee, and K.E. Lesniak. 2012. Efficacy of Westbridge Blossom Protect and Apogee in controlling fire blight on Jonathan apple, 2011. Plant Dis. Mgmt. Rep. 6:PF005.
- McGhee, G.C., and G.W. Sundin. 2012. Erwinia amylovora CRISPR elements provide new tools for evaluating strain diversity and for microbial source tracking. PLoS ONE 7:e41706.
- Malnoy, M., S. Martens, J.L. Norelli, M.-A. Barny, G.W. Sundin, T.H.M. Smits, and B. Duffy. 2012. Fire blight: applied genomic insights of the pathogen and host. Annu. Rev. Phytopathol. 50:475-494.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management, and our research focused on fire blight in 2009. ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. This work confirmed the efficacy of the experimental antibiotic kasugamycin for blossom blight control under Michigan conditions. Levels of control were similar to those observed with streptomycin, the industry standard. Additional experimental treatments using various biological control agents resulted in increased control compared to nontreated trees; however, these materials were not as effective as kasugamycin or streptomycin. We continue to pursue several lines of basic research aimed at fully understanding the interaction of the fire blight pathogen Erwinia amylovora with its apple host at the molecular level. Using a genetic approach, we uncoupled biofilm formation from the essential pathogenicity factor amylovoran exopolysaccharide to show that biofilm formation itself is critical for pathogen colonization of xylem vessels in apple. Evaluation of the role of attachment in E. amylovora biofilm formation and virulence was examined through the analysis of deletion mutants of genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based on in silico analyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment of E. amylovora to surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Results are disseminated to the research community via refereed publications in journals and through refereed research reports published in Plant Disease Management Reports. Results are disseminated to the grower community through presentations given at grower meetings and field days and through newsletter articles published in the Michigan State University MSUE News website and in trade magazines. EVENTS: Research presentations at scientific meetings included one presentation at the American Phytopathological Society North Central Division meeting, three presentations at the American Phytopathological Society national meeting, one presentation at the Resistance 2011 meeting in Rothamsted, United Kingdom, and one presentation at the Ontario Pest Management Conference. A total of 9 grower training sessions and 4 sessions targeting industry fruit extension workers were given on fire blight disease control and 4 training sessions were given on bacterial spot and bacterial canker control. PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Luisa Castiblanco - graduate student - designed and performed research related to the DspF chaperone and DspE effector. Jessica Koczan - graduate student -- designed and performed research related to the importance of biofilms for fire blight disease. Ryan McNally - graduate student - designed and performed research related to the DspF chaperone. TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we found that the experimental antibiotic material kasugamycin was efficacious for fire blight control under field conditions. We determined that biofilm formation by Erwinia amylovora was a critical pathogenicity factor and contributed to the colonization and systemic spread of the bacterium through apple xylem vessels. CHANGE IN ACTIONS: Experimental antibiotics are examined for fire blight efficacy due to the occurrence of streptomycin resistance in orchard populations of E. amylovora in Michigan. Dissemination of this knowledge to Michigan apple growers has enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures. Our work has provided the necessary data for the state of Michigan to submit emergency requests to the Environmental Protection Agency for exemptions such that Michigan growers can utilize kasugamycin for fire blight control.
Publications
- Wang, D., M. Qi, B. Calla, S.S. Korban, S. Clough, P.J.A. Cock, G.W. Sundin, I.K. Toth, and Y. Zhao. 2012. Genome-wide identification of genes regulated by the Rcs phosphorelay system in Erwinia amylovora. Molecular Plant-Microbe Interactions (in press).
- McNally, R.R., I.K. Toth, P.J.A. Cock, L.Pritchard, P.E. Hedley, J.A. Morris, Y. Zhao, and G.W. Sundin. 2012. Genetic characterization of the HrpL regulon of the fire blight pathogen Erwinia amylovora reveals novel virulence factors. Molecular Plant Pathology (in press).
- Koczan, J.M., B.R. Lenneman, M.J. McGrath, and G.W. Sundin. 2011. Cell surface attachment structures contibute to biofilm formation and xylem colonization by Erwinia amylovora. Applied and Environmental Microbiology 77:7031-7039.
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2011. Fire blight control on Jonathan apple with Kasumin in 2010. Plant Dis. Mgmt. Rep. 5:PF022.
- McGhee, G.C., K.E. Lesniak, G.W. Sundin, and G.R. Ehret. 2011. Efficacy of the bacterial antagonist, Westbridge and Phostrol in controlling fire blight on Jonathan apple in 2010. Plant Dis. Mgmt. Rep. 5:PF044.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management, and our research focused on fire blight in 2009. ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. This work confirmed the efficacy of the experimental antibiotic kasugamycin for blossom blight control under Michigan conditions. Levels of control were similar to those observed with streptomycin, the industry standard. Additional experimental treatments using various biological control agents resulted in increased control compared to nontreated trees; however, these materials were not as effective as kasugamycin or streptomycin. We have also developed a PCR detection method to identify the two specific streptomycin-resistant strains of E. amylovora that are spreading throughout Michigan apple orchards. We continue to pursue several lines of basic research aimed at fully understanding the interaction of the fire blight pathogen Erwinia amylovora with its apple host at the molecular level. We constructed a structural model of DspF, and used site-direected mutagenesis to analyze the role of specific surface amino acid residues in the DspF-DspE interaction. This work is essential to the understanding of how the major pathogenicity protein DspE is targeted from the pathogen into the host plant cells. We also determined that biofilm formation is critical to the pathogenesis of E. amylovora in causing fire blight. Using a genetic approach, we uncoupled biofilm formation from the essential pathogenicity factor amylovoran exopolysaccharide to show that biofilm formation itself is critical for pathogen colonization of xylem vessels in apple. Results are disseminated to the research community via refereed publications in journals and through refereed research reports published in Plant Disease Management Reports. Results are disseminated to the grower community through presentations given at grower meetings and field days and through newsletter articles published in the Michigan State University IPM CAT Alert and in trade magazines. EVENTS: Research presentations at scientific meetings included three presentations at the American Phytopathological national meeting, five presentations at the International Fire Blight meeting, and one presentation each at the International Pseudomonas syringae meeting and at the Spanish Phytopathological Congress. A total of 11 grower training sessions and 2 sessions targeting industry fruit extension workers were given on fire blight disease control and 2 training sessions were given on bacterial spot and bacterial canker control. PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Lindsay Triplett - graduate student - designed and performed research related to the DspF chaperone and DspE effector. Jessica Koczan - graduate student -- designed and performed research related to the importance of biofilms for fire blight disease. Ryan McNally - graduate student - designed and performed research related to the DspF chaperone. Molly McGrath - postdoctoral research associate - designed and performed research research related to the importance of biofilms for fire blight disease. TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we found that the experimental antibiotic material kasugamycin was efficacious for fire blight control under field conditions. We determined that biofilm formation by Erwinia amylovora was a critical pathogenicity factor and contributed to the colonization and systemic spread of the bacterium through apple xylem vessels. CHANGE IN ACTIONS: Experimental antibiotics are examined for fire blight efficacy due to the occurrence of streptomycin resistance in orchard populations of E. amylovora in Michigan. We have tracked the spread of streptomycin-resistant E. amylovora in Michigan for six years. Dissemination of this knowledge to Michigan apple growers has enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures. Our work has provided the necessary data for the state of Michigan to submit emergency requests to the Environmental Protection Agency for exemptions such that Michigan growers can utilize kasugamycin for fire blight control.
Publications
- McGhee, G.C., J. Guasco, L.M. Bellomo, S.E. Blumer-Schuette, W.W. Shane, A. Irish-Brown, and G.W. Sundin. 2011. Genetic analysis of streptomycin-resistant (SmR) strains of Erwinia amylovora suggests that dissemination of two genotypes is responsible for the current distribution of SmR E. amylovora in Michigan. Phytopathology 101: (in press).
- McGhee, G.C., and G.W. Sundin. 2011. Evaluation of kasugamycin for fire blight management, effect on nontarget bacteria, and assessment of kasugamycin resistance potential in Erwinia amylovora. Phytopathology 101: (in press).
- Triplett, L.R., W.J. Wedemeyer, and G.W. Sundin. 2010. Homology-based modeling of the Erwinia amylovora type III chaperone DspF used to identify amino acids required for virulence and interaction with the effector DspE. Research in Microbiology 161:613-618.
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2010. Fire blight control on Jonathan apple with antibiotics in 2009. Plant Dis. Mgmt. Rep. 4:PF006.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management, and our research focused on fire blight in 2009. ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. This work confirmed the efficacy of the experimental antibiotic kasugamycin for blossom blight control under Michigan conditions. Levels of control were similar to those observed with streptomycin, the industry standard. Additional experimental treatments using various biological control agents resulted in increased control compared to nontreated trees; however, these materials were not as effective as kasugamycin or streptomycin. We continue to pursue several lines of basic research aimed at fully understanding the interaction of the fire blight pathogen Erwinia amylovora with its apple host at the molecular level. Work identified and characterized a binding site in the major effector protein DspE for the chaperone DspF. This work is essential to the understanding of how DspE is targeted from the pathogen into the host plant cells. We also determined that biofilm formation is critical to the pathogenesis of E. amylovora in causing fire blight. Using scanning electron microscopy, we analyzed the colonization of xylem vessels by E. amylovora, demonstrating that biofilms fill the vessels contributing to the wilt symptom of fire blight. Using a genetic approach, we showed that the amylovoran exopolysaccharide is essential for biofilm formation and for disease, and that the levan exopolysaccharide contributes to biofilm formation and is a virulence factor. Results are disseminated to the research community via refereed publications in journals and through refereed research reports published in Plant Disease Management Reports. Results are disseminated to the grower community through presentations given at grower meetings and field days and through newsletter articles published in the Michigan State University IPM CAT Alert and in trade magazines. EVENTS: Research presentations at scientific meetings included four presentations at the American Phytopathological national meeting and one presentation each at the International Society for Molecular Plant-Microbe Interactions and International Congress of Plant Biology meetings in 2009. A total of 12 grower training sessions and 2 sessions targeting industry fruit extension workers were given on fire blight disease control and 2 training sessions were given on bacterial spot and bacterial canker control. PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Lindsay Triplett - graduate student - designed and performed research related to the DspF chaperone and DspE effector. Jessica Koczan - graduate student -- designed and performed research related to the importance of biofilms for fire blight disease. TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we found that the experimental antibiotic material kasugamycin was efficacious for fire blight control under field conditions. We determined that biofilm formation by Erwinia amylovora was a critical pathogenicity factor and contributed to the systemic spread of the bacterium through apple xylem vessels. CHANGE IN ACTIONS: Experimental antibiotics are examined for fire blight efficacy due to the occurrence of streptomycin resistance in orchard populations of E. amylovora in Michigan. We have tracked the spread of streptomycin-resistant E. amylovora in Michigan for six years. Dissemination of this knowledge to Michigan apple growers has enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures. Our work has provided the necessary data for the state of Michigan to submit emergency requests to the Environmental Protection Agency for exemptions such that Michigan growers can utilize kasugamycin for fire blight control.
Publications
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2009. Fire blight control on Jonathan apple with antibiotics in 2008. Plant Dis. Manag. Rpt. 3:PF027.
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2009. Efficacy of bacterial antagonists in controlling fire blight on Gala apple in 2008. Plant Dis. Manag. Rpt. 3:PF028.
- Koczan, J.M., M.J. McGrath, Y. Zhao, and G.W. Sundin. 2009. Contribution of Erwinia amylovora exopolysaccharides amylovoran and levan to biofilm formation: implications in pathogenicity. Phytopathology 99:1237-1244.
- Triplett, L.R., M. Maelotto, and G.W. Sundin. 2009. Functional analysis of the N terminus of the Erwinia amylovora secreted effector DspA/E reveals features required for secretion, translocation, and binding to the chaperone DspB/F. Mol. Plant-Microbe Interact. 22:1282-1292.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management, and our research focused on fire blight in 2008. ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple and pear. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. This work confirmed the efficacy of the experimental antibiotic kasugamycin for blossom blight control under Michigan conditions. Levels of control were similar to those observed with streptomycin, the industry standard. Additional experimental treatments using various biological control agents resulted in a significant level of control compared to nontreated trees; however, these materials were not as effective as kasugamycin or streptomycin. We continue to pursue several lines of basic research aimed at fully understanding the interaction of the fire blight pathogen Erwinia amylovora with its apple host at the molecular level. Work in 2008 studied the role of lipopolysaccharide (LPS) in the disease process, examined the role of the ubiquitous plasmid pEA29 in the virulence of E. amylovora, studied the mechanism of action of the growth inhibitor prohexadione-calcium on shoot blight disease control, and determined the role of biofilms in fire blight disease. Using an LPS-deficient mutant of E. amylovora, we showed that the LPS served as a virulence factor during infection and also protected cells from oxidative stress. Results are disseminated to the research community via refereed publications in journals and through refereed research reports published in Plant Disease Management Reports. Results are dissemianted to the grower community through presentations given at grower meetings and field days and through newsletter articles published in the Michigan State University IPM CAT Alert and in trade magazines. EVENTS: Research presentations at scientific meetings included four presentations at the American Phytopathological national meeting and one presentation at the International Congress of Plant Pathology in 2008. A total of 13 grower training sessions were given on fire blight disease control. PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Youfu Zhao - postdoctoral research associate -- responsible for work on the role of lipopolysaccharide in fire blight disease. Matthew Berry -- graduate student -- responsible for work on the role of lipopolysaccharide in fire blight disease. TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we found that the experimental antibiotic material kasugamycin was efficacious for fire blight control under field conditions. We determined that the lipopolysaccharide layer of Erwinia amylovora was an important virulence factor and contributed to the survival of the bacterium when exposed to elevated levels of hydrogen peroxide. CHANGE IN ACTIONS: Experimental antibiotics are examined for fire blight efficacy due to the occurrence of streptomycin resistance in orchard populations of E. amylovora in Michigan. We have tracked the spread of streptomycin-resistant E. amylovora in Michigan for six years. Dissemination of this knowledge to Michigan apple growers has enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures. Our work has provided the necessary data for the state of Michigan to submit emergency requests to the Environmental Protection Agency for exemptions such that Michigan growers can utilize new materials for fire blight control.
Publications
- Berry, M.C., G.C. McGhee, Y. Zhao, and G.W. Sundin. 2009. Effect of a waaL mutation on lipopolysaccharide composition, oxidative stress survival, and virulence in Erwinia amylovora. FEMS Microbiol. Lett. (in press).
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2008. Efficacy of bacterial antagonists in controlling fire blight on Jonathan apple, 2007. Plant Dis. Manag. Rep. 2:PF014.
- Sundin, G.W., G.R. Ehret, and G.C. McGhee. 2008. Control of fire blight on Jonathan apple with antibiotics in 2007. Plant Dis. Manag. Rep. 2:PF015.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: ACTIVITIES: Experiments conducted included work on short-term control methods for fire blight disease of apple and pear. We examined the efficacy of experimental antibiotics and biological control agents for blossom blight control. Additional experiments included analyses of the distribution of streptomycin resistant strains of the pathogen Erwinia amylovora in Michigan and characterization of the mechanism of streptomycin resistance in these strains. We also continued work examining the role of the ubiquitous plasmid pEA29 in the virulence of E. amylovora, studied the mechanism of action of the growth inhibitor prohexadione-calcium on shoot blight disease control, and began studies examining the role of biofilms in fire blight disease. EVENTS: Research presentations at scientific meetings included four presentations at the American Phytopathological national meeting in 2007 and six presentations at the International Fire Blight Working Group meeting in 2007. A total of 10
grower training sessions were given on fire blight disease control. DISSEMINATION: Outreach activities included oral presentations given to growers and other clientele at grower meetings, newsletter type articles published through Michigan State University IPM CAT Alert, and informal one-on-one meetings with individual growers through on-farm visits.
PARTICIPANTS: George Sundin -- PI -- oversees all research projects, makes oral presentations at grower meetings, writes extension/newsletter articles, co-writes research publications. Gail Ehret -- laboratory research technician -- responsible for field projects relating to fire blight disease control. Gayle McGhee -- laboratory research assistant -- responsible for field projects relating to fire blight disease control and studies of streptomycin resistance in Erwinia amylovora in Michigan. Molly McGrath -- postdoctoral research associate -- responsible for experiments aimed at determining the mechanism of action of prohexadione-calcium for fire blight control. Jessica Koczan -- graduate student -- responsible for work on the role of biofilms in fire blight disease.
TARGET AUDIENCES: The target audience for this work is the grower community (apple, cherry, peach), extension agents, representatives for chemical companies and disease scouting consultants, mainly in Michigan but in other states as well. Additional target audience is the research community of plant pathologists that work on bacterial diseases of tree fruit.
PROJECT MODIFICATIONS: None.
Impacts
CHANGE IN KNOWLEDGE: Through this work, we learned of the spread of streptomycin resistance in E. amylovora into new areas of Michigan; we also learned that the spread of resistant strains in other areas was more limited than previously predicted. We found that new materials were efficacious for fire blight control under field conditions. We determined that the role of pEA29 in virulence of the fire blight pathogen was mainly due to the impact of the thiamin-biosynthetic genes of the plasmid on the expression of exopolysaccharide biosynthesis genes involved in biofilm formation. CHANGE IN ACTIONS: By disseminating information on streptomycin resistance directly to growers, we enabled these growers to change fire blight management practices and thus not be exposed to the possibility of catastrophic losses due to disease control failures.
Publications
- Kennelly, M.M., F.M. Cazorla, A. de Vicente, C. Ramos, and G.W. Sundin. 2007. Pseudomonas syringae diseases of fruit trees: progress towards understanding and control. Plant Dis. 91:4-17.
- Ehret, G.R., G.W. Sundin, and G.C. McGhee. 2007. Fire blight control on Gala apple in 2006. Plant Dis. Manage. Rep. 1:PF036.
- Ehret, G.R., G.W. Sundin, and G.C. McGhee. 2007. Antibiotic treatments on Gala apple for the control of fire blight in 2006. Plant Dis. Manage. Rep. 1:PF037.
- Ehret, G.R., G.W. Sundin, and G.C. McGhee. 2007. Efficacy of bacterial antagonists in controlling fire blight on Jonathan apple in 2006. Plant Dis. Manage. Rep. 1:PF038.
- Ehret, G.R., G.W. Sundin, and G.C. McGhee. 2007. Biological control of fire blight on Jonathan apple in 2006. Plant Dis. Manage. Rep. 1:PF039.
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Progress 01/01/06 to 12/31/06
Outputs
Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management. Regarding fire blight, we have focused on optimizing the management of this disease through control of the blossom blight phase. These are the compounds we have been testing for fire blight control: copper bactericides, the antibiotics streptomycin, oxytetracycline, kasugamycin, and gentamicin, the growth regulator prohexadione-calcium, the fungicide famoxate, the host resistance elicitor laminarin, and the biological control agents Serenade, BlightBan, Bloomtime, and Pantoea agglomerans C9-1. Streptomycin is the most effective fire blight control available; however, we have detected streptomycin-resistant strains of Erwinia amylovora in two important fruit-growing areas of Michigan. Oxytetracycline is less effective
than streptomycin, but remains the best alternative in orchards where streptomycin resistance is a problem. Copper is an effective early season bactericide, but cannot be used later due to problems with fruit russeting. The biological control options were partially effective in fire blight control in our 2006 experiments. Prohexadione calcium was highly effective in reducing the shoot blight phase of the disease. The bactericide control programs must be combined with growing varieties that are less susceptible to fire blight in order to achieve high levels of control. In terms of genetic analyses, we have completed a study in which approximately 394 E. amylovora genes that are induced during infection were identified. We identified two new effector genes, avrRpt2EA and hopPtoCEA, and several other candidate virulence genes. We demonstrated that avrRpt2EA was similar to the homologous effector protein from Pseudomonas syringae and functioned similarly in eliciting the hypersensitive
response in Arabidopsis plants containing the RPS2 resistance gene. We performed experiments aimed at identifying genes contributing to host specificity in E. amylovora by isolating genes unique to apple pathogenic strains and not present in raspberry pathogenic strains. We continued our work on the role of the ubiquitous plasmid pEA29 in virulence. This study has shown that the thiOGF genes are the critical genes on pEA29 in controlling the virulence effect of this plasmid. In addition, we continue to focus our efforts on determining the function of DspE, the critical effector for disease.
Impacts
This research is aimed at determining sound management practices for controlling bacterial diseases of tree fruits. Effective management is difficult due to the lack of available compounds, the growth of highly disease-susceptible varieties, and bactericide resistance. We have developed optimized control programs for these diseases based on currently-available compounds.
Publications
- Triplett, L.R., Y. Zhao, and G.W. Sundin. 2006. Genetic differences between blight-causing Erwinia species with differing host specificities, identified by suppression subtractive hybridization. Appl. Environ. Microbiol. 72:7359-7364.
- Sundin, G.W., G.C. McGhee, G.C. Foster, and A.L. Jones. 2006. Genetic analysis of the ubiquitous plasmid pEA29 and two new Erwinia amylovora plasmids. Acta Hortic. 704:423-430.
- Zhao, Y., S.-Y. He, and G.W. Sundin. 2006. The Erwinia amylovora avrRpt2EA gene contributes to virulence on pear and AvrRpt2EA is recognized by Arabidopsis RPS2 when expressed in Pseudomonas syringae. Mol. Plant-Microbe Interact. 19:644-654.
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Progress 01/01/05 to 12/31/05
Outputs
Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management. Regarding fire blight, we have focused on optimizing the management of this disease through control of the blossom blight phase. These are the compounds we have been testing for fire blight control: copper bactericides, the antibiotics streptomycin, oxytetracycline, and gentamicin, the growth regulator prohexadione-calcium, the fungicide famoxate, the host resistance elicitor laminarin, and the biological control agents Serenade, BlightBan, and Pantoea agglomerans C9-1. Streptomycin is the most effective fire blight control available; however, we have detected streptomycin-resistant strains of Erwinia amylovora in two important fruit-growing areas of Michigan. Oxytetracycline is less effective than streptomycin, but
remains the best alternative in orchards where streptomycin resistance is a problem. Copper is an effective early season bactericide, but cannot be used later due to problems with fruit russeting. The compounds famoxate and laminarin show promise, but need to be tested again in 2006. The biological control options were partially effective in fire blight control. Prohexadione calcium was highly effective in reducing the shoot blight phase of the disease. The bactericide control programs must be combined with growing varieties that are less susceptible to fire blight in order to achieve high levels of control. We examined the efficacy of copper in a bacterial canker management program but found that, because copper cannot be sprayed during bloom, bacterial populations quickly recover on blossoms following early-season copper applications. A large-scale survey of Michigan sweet cherry orchards revealed that populations of the pathogen Pseudomoans syringae are quite large on blossoms
throughout the state. Analyses of copper resistance in P. syringae and the bacterial spot pathogen Xanthomonas arbicola pv. pruni (Xap) revealed high levels of copper resistance in Xap only. In terms of genetic analyses, we have completed a study in which approximately 160 E. amylovora genes that are induced during infection were identified. We identified a new effector gene, hopPtoCEA, and several other candidate virulence genes. We continued our work on the role of the ubiquitous plasmid pEA29 in virulence. We have shown that expression of many of the promoters of pEA29 genes is induced during infection and are currently constructing knockout mutations in several of the genes for functional characterization. This study has shown that the thiOGF genes are the critical genes on pEA29 in controlling the virulence effect of this plasmid. In addition, we continue to focus our efforts on determining the function of DspE, the critical effector for disease.
Impacts
This research is aimed at determining sound management practices for controlling bacterial diseases of tree fruits. Effective management is difficult due to the lack of available compounds, the growth of highly disease-susceptible varieties, and bactericide resistance. We have developed optimized control programs for these diseases based on currently-available compounds.
Publications
- Zhao, Y., S.E. Blumer, and G.W. Sundin. 2005. Identification of Erwinia amylovora genes induced during infection of immature pear tissue. J. Bacteriol. 187:8088-8103.
- Sundin, G.W., and G.R. Ehret. 2005. Control of fire blight on Jonathan and Golden Delicious apple in 2004. Fungic. Nematic. Tests 60:PF033.
- Sundin, G.W., G.R. Ehret, and W.W. Shane. 2005. Evaluation of bactericides for fire blight control in a commercial orchard near Benton Harbor, Michigan, 2004. Fungic. Nematic. Tests 60:PF038.
- Sundin, G.W., and G.R. Ehret. 2005. Fire blight control with Gowan products in 2004. Fungic. Nematic. Tests 60:PF034.
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Progress 01/01/04 to 12/31/04
Outputs
Fire blight of apple and pear, bacterial canker of sweet and tart cherry, and bacterial spot of peach are the three most important tree fruit bacterial diseases in Michigan. My group is working with short and long-term applications for disease management. Regarding fire blight, we have focused on optimizing the management of this disease through control of the blossom blight phase. These are the compounds we have been testing for fire blight control: copper bactericides, the antibiotics streptomycin, oxytetracycline, and gentamicin, the growth regulator prohexadione-calcium, and the biological control agents Serenade, BlightBan, and Pantoea agglomerans C9-1. Streptomycin is the most effective fire blight control available; however, we have detected streptomycin-resistant strains of Erwinia amylovora in two important fruit-growing areas of Michigan. Oxytetracycline is less effective than streptomycin, but remains the best alternative in orchards where streptomycin
resistance is a problem. Copper is an effective early season bactericide, but cannot be used later due to problems with fruit russeting. The biological control options were partially effective in fire blight control. Prohexadione calcium was highly effective in reducing the shoot blight phase of the disease. The bactericide control programs must be combined with growing varieties that are less susceptible to fire blight in order to achieve high levels of control. We examined the efficacy of copper in a bacterial canker management program but found that, because copper cannot be sprayed during bloom, bacterial populations quickly recover on blossoms following early-seaseon copper applications. A large-scale survey of Michigan sweet cherry orchards revealed that populations of the pathogen Pseudomoans syringae are quite large on blossoms throughout the state. Analyses of copper resistance in P. syringae and the bacterial spot pathogen Xanthomonas arbicola pv. pruni (Xap) revealed high
levels of copper resistance in Xap only.
Impacts
This research is aimed at determining sound management practices for controlling bacterial diseases of tree fruits. Effective management is difficult due to the lack of available compounds, the growth of highly disease-susceptible varieties, and bactericide resistance. We have developed optimized control programs for these diseases based on currently-available compounds.
Publications
- No publications reported this period
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