Fernando: Optimizing Canola Production Through Biological Control of Virulent Strains of Blackleg Leptosphaeria Maculans & Insect Pests of Canola
Date: March 2007
Term: n/a
Status: Completed
Researcher(s): Dr. Dilantha Fernando, Professor, Plant Science, Principle Investigator; Dr. Neil Holliday, Professor and Head, Entomology, Co-investigator; Graduate students: Rajesh Ramarathnam (PhD), Yu Chen (PhD), Department of Plant Science; Kate Bergen, Department of Entomology, University of Manitoba, Winnipeg
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
In this research project, the two main objectives were to investigate the responses of major insect pests and the Blackleg pathogen of canola to the two bacterial strains, Pseudomonas chlororaphis (PA23) and Bacillus amyloliquifaciens (BS6), plus jasmonic acid. Overall this study identified bacterial antagonists that could be potential biocontrol agents against the blackleg and sclerotinia.
The pathogen Leptosphaeria maculans causes blackleg disease in canola. Researchers are interested in finding potential biological control agents for blackleg and other diseases such as sclerotinia. In this research project, the objective was to investigate the responses of major insect pests of canola to the two bacterial strains, Pseudomonas chlororaphis (PA23) and Bacillus amyloliquifaciens (BS6) and to Blackleg disease.
Bacillus amyloliquefacians strain BS6: The bacterium we have isolated and have shown to be an excellent biocontrol agent against both Sclerotinia and Blackleg is the rhizosphere strain Bacillus amyloliquefacians strain BS6 and a few other Bacillus endophytes3,4,5,6,7. MALDI-TOF mass spectroscopy showed that BS6 produces four antibiotics, zwittermicin A, surfactin, bacillomycin D and fengycins3. Both B. amyloliquefaciens and B. Cereus were able to control the Blackleg pathogen by direct antibiosis but also had a significant but a lesser effect by induced resistance2. Further studies are needed to explore and learn from these Bacillus strains. Extensive use of pesticides could have adverse effects on the environment. Biological control offers a friendlier alternative. As biological products are accepted by farmers (Contans, Serenade) the future markets for our bacterial products look promising.
Pseudomonas cholororaphis strain PA23 has been the most studied bacterium in our lab4,5,6. Using antibiotic-specific PCR primers and HPLC we have been able to deduce the production of phenazine 1-carboxylic acid, 2-hydroxyphenazine and pyrrolnitrin25. PA23 produced protease, lipase, hydrogen cyanide and siderophores23. PA23 also forms biofilms7. Through the excellent collaboration with Dr. Teri de Kievit’s Microbiology laboratory, we have employed transposon mutagenesis, and shown a GacS deficiency does not affect PA23 fitness on canola plants or as a biofilm7. Also, the mutant was not able to protect the canola from the sclerotinia and Blackleg pathogens2,1. Another key finding from the work on PA23 was that phenazines are not essential for biocontrol of sclerotinia and blackleg but pyrrolnitirn is1,2. However, phenazines play a key role in biofilm formation.
Insect pests and management through bacterial biocontrol strains and jasmonic acid: - conducted with Dr. Neil Holliday (Entomology) and Kate Bergen (Graduate Student) Strains of some plant growth promoting rhizobacteria (PGPR) can inhibit plant pathogens. Two PGPR strains, Pseudomonas chlororaphis (PA23) and Bacillus amyloliquifaciens (BS6) have been shown to control some fungal diseases of canola. PGPR control pathogens through the production of bacterial metabolites and volatile compounds and through induced systemic resistance, which is initiated by the signaling molecule jasmonic acid, and can protect plants against multiple pest threats. Direct application of jasmonic acid has been shown to activate defense compounds and influence insect herbivory in canola. Field and laboratory studies were carried out to investigate the effects of the two bacteria and of jasmonic acid on insects of canola.
The results of the laboratory experiments using diamondback moths (Plutella xylostella) and turnip aphids (Lipaphis erysimi) showed that there were significant treatment effects, with significantly lower area consumed by larvae on the jasmonic acid treated plants, and larval weights were significantly lower for those larvae feeding on jasmonic acid treated plants. Laboratory experiments found that jasmonic acid significantly affects oviposition and larval feeding in the diamondback moth (Plutella xylostella) and development and reproduction in the turnip aphid (Lipaphis erysimi).
Field studies did not find any significant effects of treatment on any of the insects sampled or on level of flea beetle injury, cabbage maggot parasitism or canola yield or quality.
Overall this study identified bacterial antagonists that were involved in suppression of L. maculans (Blackleg pathogen of canola) and S. sclerotiorum (stem rot pathogen of canola). Researchers received additional funding to continue the laboratory studies and larval experiments from NSERC (Discovery grant to Dilantha Fernando) and ARDI Manitoba.
Scientific Publications
Athukorala, S.N.P., Fernando, W.G.D. and Rashid, K. 2009 Identification of antifungal antibiotics of Bacillus species isolated from different microhabitats using Polymerase Chain Reaction and MALDI-TOF mass spectrometry. Can J Microbiology 55:1021–32.
Fernando, W.G.D., Zhang, Y., Nakkeeran, S., and Savchuk, S. 2007. Biological control of Sclerotinia sclerotiorum (Lib.) de Bary by Pseudomonas and Bacillus species on canola petals Crop Protection 26:100-107.
Poritsanos, N., Selin, C., Fernando, W.G.D., Nakkeeran, S. and de Kievit, T.R. 2006. A GacS deficiency does not affect Pseudomonas chlororaphis PA23 fitness when growing on canola, in aged batch culture or as a biofilm. Can J of Microbiology 52:1177-1182.
Ramarathnam, R., de Kievit, T. and Fernando, W.G.D. 2010. The role of antibiosis and induced systemic resistance, mediated by strains of Pseudomonas chlororaphis, Bacillus cereus and B. amyloliquefaciens, in controlling blackleg disease of canola. BioControl (in press)
Ramarathnam, R., Shen, B. Fernando, W.G.D., Chen, Y., de Kievit, T. and Gao, X. 2007. PCR-based detection and biochemical characterization of fengycin, and bacillomycin D, producing Bacillus sp. involved in the biocontrol of fungal pathogens of canola and wheat. Canadian Journal of Microbiology 53:901-911.
Selin, C., Habibian, R., Poritsanos, N., Athukorala, S.N.P., Fernando, W.G.D. and de Kievit, T.R. 2010 Phenazines are not essential for Pseudomonas chlororaphis PA23 biocontrol of S. sclerotiorum, but do play a role in biofilm formation. FEMS Microbiology Ecology 71:73-83.
Zhang, Y., Fernando, W.G.D., de Kievit, T., Berry, C., Daayf, F., and Paulitz, T.C. 2006. Detection of antibiotic-related genes from bacterial biocontrol agents using polymerase chain reaction. Canadian Journal of Microbiology 52:476-481.