Progress 09/15/04 to 09/14/07
Outputs
OUTPUTS: Field plots that had been established to determine the long-term fate and distribution of recombinant and wild-type Pseudomonas flurorescens were monitored. Population sizes of recombinant strain Z30-97 and wild-type strain Q8r1-96 were compared in the rhizosphere environment of field-grown spring wheat. The spread of the bacteria into non-inoculated wheat and onto weeds was monitored. Field samples were collected for mass spec. analysis of the rhizosphere metabolome for the amount of 2,4-Diacetylphloroglucinol (DAPG) and phenazine-1-carboxylic acid by Q8r1-96 and Z30-97. Real-time PCR approaches were tested to detect wild-type populations of Q8r1-96. PARTICIPANTS: PI/PD: David M. Weller, Stacey Blowin-Bankhead, Linda S. Thomashow, Robert F. Bonsall, Dmitri V. Mavrodi, Olga V. Mavrodi TARGET AUDIENCES: Scientists worldwide, Regulatory agencies, Growers, and Private Industry PROJECT MODIFICATIONS: none
Impacts
Wheat and barley grown in the U.S. is infected by root diseases, resulting in yield reductions of 10 to 30% annually and billions of dollars in losses to American farmers. Plants with root diseases cannot take full advantage of fertilizers and irrigation water applied by farmers, and unused nitrates move into surface and ground water. Root diseases are especially severe when several crops of wheat or barley are planted before a break crop, and when they are direct-seeded into their own stubble (no-till). More effective root disease control will allow farmers to reap the economic benefits associated with intensive cereal cropping and the benefits of soil erosion control associated with direct seeding. Wheat and barley lack resistance to most root diseases. Chemical pesticides are either too expensive or ineffective and concerns about their adverse effects on the environment and public health are increasing. Biocontrol is the best alternative to control root diseases, but its use is hindered by inconsistent performance. The use of genetically-engineered or modified Pseudomonas biocontrol agents is one approach to improve biocontrol activity and lower the dose of inoculum needed to achieve disease suppression. This research aims to determine the long-term impact and survival and spread of transgenic biocontrol agents in the field. When introduced individually, a genetically engineered biocontrol agent survived no better than the non-engineered parental strains in the rhizosphere of wheat, barley, navy bean and pea. However, in dual inoculations the parental strain displaced the transgenic biocontrol agent in the wheat and barley rhizospheres but the transgenic strain out-competed the parental strain in the pea rhizosphere. In the navy bean rhizosphere, the wild-type and transgenic had equivalent population sizes in dual inoculation studies. Results from a multi-year field study where the transgenic was introduced only in the first year indicated that the transgenic does not pose a threat of long term survival in the soil at high densities. However, the introduced transgenic strain, like the wild-type strain, is able to spread throughout the field to plants that were not originally inoculated. However, weed species commonly found in cereal-based cropping systems were not colonized by either the wild-type or recombinant strains. Adding multiple biocontrol genes into a wild-type strain can lead to a significant reduction in the ecological fitness of the transgenic strain in the wheat rhizosphere, probably because production of the additional antibiotics places a significant burden on the metabolism of the recombinant strain. Mass spec analysis of extracts from the rhizosphere of wheat colonized either by Q8r1-96, Z30-97 or Z15-02 (recombinant that produces DAPG, PCA and 2-hydroxy PCA) showed detectable amounts of PCA and DAPG in the rhizospheres colonized by by Z30-97 and Z15-02 but no detectable DAPG in the rhizosphere with Q8r1-96. This research continues to provide regulatory agencies with the information needed to determine the safety of recombinant biocontrol agents introduced into agroecosystems.
Publications
- Blouin-Bankhead, S., Landa, B., Lutton, E., Weller, D.M., and McSpadden Gardener, B.B. (2004). Minimal changes in rhizobacterial population structure following root colonization by wild type and transgenic biocontrol strains. FEMS Microbiology Ecol. 49 (2):307-318.
- Blouin Bankhead, S., Schroeder, K., Son, M.Y., Thomashow, L.S., Weller, D.M., 2005. Population dynamics and movement of transgenic Pseudomonas fluorescens in the rhizosphere of field-grown wheat. In: Hartmann, A., Schmid, M., Wenzel, W., Hinsinger, Ph. (Eds.), Rhizosphere 2004: Perspectives and Challenges-A Tribute to Lorenz Hiltner. GSF-Forschungszentrum, p. 165.
- Thomashow, L.S., and Weller, D.M. (2005) Sustainable use of microbial genetic resources in agriculture: biological control agents. Agrociencia: 9:317-320.
- Blouin Bankhead, S., Son, M., Thomashow, L., and Weller, D. (2005). Population dynamics of transgenic Pseudomonas fluorescens in the rhizosphere of field-grown wheat Phytopathology 95:S11
- Thomashow, L.S., Weller, D.M., Mavrodi, O.V., and Mavrodi, D.V. (2007) Selecting, monitoring, and enhancing the performance of bacterial biocontrol agents: principles, pitfalls, and progress. pp. 87-105 in: M. Vurro and J. Gressel (ed.). Novel Biotechnologies for Biocontrol Agent Enhancement and Management. Springer. 2007.
- Huang, Z., Bonsall, R.F., Mavrodi, D.V., Weller, D.M., and Thomashow, L.S. (2004). Transformation of Pseudomonas fluorescens with genes for biosynthesis of phenazine-1-carboxylic acid improves biocontrol of Rhizoctonia root rot and in situ antibiotic production. FEMS Microbiol. Ecol. 49 (2):243-251.
- Bonsall, R. F., Thomashow, L. S., Mavrodi, D. V., and D. M. Weller. (2007). Extraction and detection of antibiotics in the rhizosphere metabolome. LC GC North America 11:14-19.
- Mavrodi, O. V., Mavrodi, D. V., Thomashow, L. S., and Weller, D. M. (2007). Quantification of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens strains in the plant rhizosphere by real-time PCR. Appl. Environ. Microbiol. 73 (9):5531-5538.
|
Progress 10/01/05 to 09/30/06
Outputs
OUTPUTS: Field plots that had been established to determine the long-term fate and distribution of recombinant and wild-type Pseudomonas fluorescens were monitored. Population sizes of recombinant strain Z30-97 and wild-type strain Q8r1-96 were compared in the rhizosphere environment of spring wheat. The spread of the bacteria into non-inoculated plots was monitored. Field samples were collected for mass spec. analysis to determine the amounts of 2,4-diacetylphloroglucinol and phenazine-1-carboxylic acid produced by wild-type and recombinant strains. Presented Poster (P66): Rhizosphere colonization of transgenic and wild-type Pseudomonas fluorescens is modulated by the crop species, S. Blouin Bankhead, J. M. Peterson, M. Y. Son, L.S. Thomashow and D.M. Weller at the 7th Intrnational Workshop on Plant Growth Promoting Rhizobacteria, Noordwijderhout, The Netherlands, 2006. PARTICIPANTS: PI/PD: David M. Weller, Stacey Blouin-Bankhead, Linda S. Thomashow, Robert F. Bonsall, Dmitri V. Mavrodi, Olga V. Mavrodi. TARGET AUDIENCES: Scientists worldwide, Regulatory agencies, Growers and Private Industry. PROJECT MODIFICATIONS: None
Impacts
Most wheat and barley grown in the U.S. is infected by root diseases, resulting in yield reductions of 10 to 30% annually and over a billion dollars in losses to American farmers. Wheat and barley with root diseases cannot take full advantage of fertilizers and irrigation water applied by farmers, and unused nitrates move into surface and ground water. Root diseases are especially severe when several crops of wheat or barley are planted before a break crop, and when they are direct-seeded into their own stubble (no-till). More effective root disease control will allow farmers to reap the economic benefits associated with intensive cereal cropping and the benefits of soil erosion control associated with direct seeding. Wheat and barley lack resistance to most root diseases. Synthetic chemical pesticides are either too expensive or ineffective and concerns about their adverse effects on the environment and public health are increasing. Biocontrol is the best alternative to control root diseases, but its use is hindered by inconsistent performance. The use of genetically engineered Pseudomonas biocontrol agents is one approach to improve biocontrol activity and lower the dose needed to achieve disease suppression. This research aims to determine the long-term impact and survival and spread of recombinant biocontrol agents in the field. When introduced individually, a genetically engineered biocontrol agent survived no better than the non-engineered parental strains in the rhizosphere of wheat, barley, bean and pea. However, in dual inoculations the parental strain displaced the engineered biocontrol agents in the wheat, barley and bean rhizospheres but the transgenic strain out-competed the parental strain in the pea rhizosphere. Results from a four-year-long field study where the transgenic was introduced only in the first year indicated that the transgenic does not pose a threat of long term survival in the soil at high densities. However, the introduced transgenic strain, like the wild-type parental strain, is able to spread throughout the field to plants that were not originally inoculated. This research provides regulatory agencies with the information needed to determine the safety of transgenic biocontrol agents introduced into agroecosystems.
Publications
- Thomashow, L.S., and Weller, D.M. (2005) Sustainable use of microbial genetic resources in agriculture: biological control agents. Agrociencia: 9:317-320.
- Blouin Bankhead, S., Son, M., Thomashow, L., and Weller, D. (2005). Population dynamics of transgenic Pseudomonas fluorescens in the rhizosphere of field-grown wheat Phytopathology 95:S11
|
Progress 10/01/04 to 09/30/05
Outputs
OUTPUTS: Field plots were established to determine the long-term fate and distribution of transgenic Pseudomonas fluorescens as compared to wild-type strains. Population sizes of transgenic strain Z30-97 and wild-type Q8r1-96 were compared in the rhizosphere of spring wheat. The spread of the bacteria into non-inoculated plots was determined. Results were presented as a poster at the meeting, Rhizosphere 2004- Perspectives and Challenges- A Tribute to Lorenz Hiltener, held in Munich, Germany. PARTICIPANTS: PI/PD: David M. Weller Stacey Blouin-Bankhead Lind S. Thomashow Robert F. Bonsall Dmitri V. Mavrodi Olga V. Marvrodi TARGET AUDIENCES: Scientists Regulatory Agencies PROJECT MODIFICATIONS: None
Impacts
Most wheat and barley grown in the U.S. is infected by root diseases, resulting in yield reductions of 10 to 30% annually and over a billion dollars in losses to American farmers. Wheat and barley with root diseases cannot take full advantage of fertilizers and irrigation water applied by farmers, and unused nitrates move into surface and ground water. Root diseases are especially severe when several crops of wheat or barley are planted before a break crop, and when they are direct-seeded into their own stubble (no-till). More effective root disease control will allow farmers to reap the economic benefits associated with intensive cereal cropping and the benefits of soil erosion control associated with direct seeding. Wheat and barley lack resistance to most root diseases. Synthetic chemical pesticides are either too expensive or ineffective and concerns about their adverse effects on the environment and public health are increasing. Biocontrol is the best alternative to control root diseases, but its use is hindered by inconsistent performance. The use of genetically engineered Pseudomonas biocontrol agents is one approach to improve biocontrol activity and lower the dose needed to achieve disease suppression. This research aims to determine the long-term impact and survival of transgenic biocontrol agents in the field. When introduced individually, a genetically engineered biocontrol agent survived no better than the non-engineered parental strains in the rhizosphere of wheat, barley, bean and pea. In dual inoculations the parental strain displaced the engineered biocontrol agents in the wheat, barley and bean rhizospheres but the transgenic strain out-competed the parental strain in the pea rhizosphere. A three-year-long field study where the transgenic was introduced only in the first year indicated that the transgenic does not pose a threat of long term survival in the soil at high densities. This research provides regulatory agencies with the information needed to determine the safety of transgenic biocontrol agents introduced into agroecosystems.
Publications
- Huang, Z., Bonsall, R.F., Mavrodi, D.V., Weller, D.M., and Thomashow, L.S. (2004). Transformation of Pseudomonas fluorescens with genes for biosynthesis of phenazine-1-carboxylic acid improves biocontrol of Rhizoctonia root rot and in situ antibiotic production. FEMS Microbiol. Ecol. 49 (2):243-251.
- Blouin-Bankhead, S., Landa, B., Lutton, E., Weller, D.M., and McSpadden Gardener, B.B. (2004) Minimal changes in rhizobacterial population structure following root colonization by wild type and transgenic biocontrol strains. FEMS Microbiology Ecol. 49 (2):307-318.
- Blouin Bankhead, S., Schroeder, K., Son, M.Y., Thomashow, L.S., Weller, D.M., 2005. Population dynamics and movement of transgenic Pseudomonas fluorescens in the rhizosphere of field-grown wheat. In: Hartmann, A., Schmid, M., Wenzel, W., Hinsinger, Ph. (Eds.), Rhizosphere 2004: Perspectives and Challenges-A Tribute to Lorenz Hiltner. GSF-Forschungszentrum, p. 165.
|
|