Progress 10/01/05 to 09/30/08
Outputs
OUTPUTS: The objectives of this project are to examine the effect of jasmonic acid-inhibition of legume nodule formation on both gene expression and nodule development. In addition, we propose to examine the effect of co-inoculation of the beneficial soil bacteria Pseudomonas fluorescens and Sinorhizobium meliloti on legume nodulation. The beneficial effect of some P. fluorescens strains has been proposed to be due to stimulation of the plant defense response via the jasmonic acid signaling pathway. We have identified a potential interaction between specific P. fluorescens strains and the formation of nitrogen fixing nodules by beneficial Sinorhizobium meliloti. Results are published in peer-reviewed journals and reported at scientific meetings. PARTICIPANTS: Two graduate students and 1 postdoctoral researcher contributed to this project. The postdoc, Vinitha Cardoza, was a coauthor on the Plant Journal publication. The two graduate students both participated in this project as rotation students. Rotation students are new graduate students who have not yet joined a thesis lab. Thus these projects served to train them in the techniques that we use regularly in our lab, and to introduce them to the questions that we consider. I expect that both will be coauthors when this work is published. With the postdoc, we focused a great deal on experimental design in this project, and I hope that it was a good learning experience for her. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We have recently published a role for jasmonic acid in regulating the earliest steps in the interaction between legumes and the beneficial bacterium, rhizobium. We are currently examining the interaction between the legume, M. truncatula, and two different beneficial bacteria, Rhizobium and P. fluorescens. Plants produce chemicals that provide a defense against disease-causing bacteria. Organic gardeners are increasingly interested in harnessing plants' native defense systems to provide natural protection against pathogens. We have found that one natural plant defense compound, jasmonic acid, not only protects against pathogenic bacteria, it also harms the plants ability to interact with beneficial bacteria. We are trying to identify the point at which jasmonic acid interferes with this beneficial interaction. Ultimately, this research could be helpful to Vermont farmers, especially organic farmers, as they try to increase interactions with beneficial bacteria and reduce bacterial disease of plant crops.
Publications
- Jongho Sun, Vinitha Cardoza, David M. Mitchell, Lydia Bright, Giles Oldroyd and Jeanne M. Harris. (2006). Crosstalk between Jasmonic acid, ethylene and Nod factor signaling allows integration of diverse inputs for regulation of nodulation. The Plant Journal, 46: 961-970.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: The objectives of this project are to examine the effect of jasmonic acid-inhibition of legume nodule formation on both gene expression and nodule development. In addition, we propose to examine the effect of co-inoculation of the beneficial soil bacteria Pseudomonas fluorescens and Sinorhizobium meliloti on legume nodulation. The beneficial effect of some P. fluorescens strains has been proposed to be due to stimulation of the plant defense response via the jasmonic acid signaling pathway. We will test whether or not P. fluorescens inhibits formation of nitrogen-fixing legume nodules.
PARTICIPANTS: Giovanna Sassi, graduate student, has worked on the P. fluorescens part of the project. In addition, Graham Burkart, an undergraduate student and then a technician in my lab, ran some nodulation assays.
TARGET AUDIENCES: The target audience for this project is other scientists and potentially organic farmers.
Impacts
We have recently published a role for jasmonic acid in regulating the earliest steps in the interaction between legumes and the beneficial bacterium, rhizobium. We are currently examining the interaction between the legume, M. truncatula, and two different beneficial bacteria, Rhizobium and P. fluorescens. Plants produce chemicals that provide a defense against disease-causing bacteria. Organic gardeners are increasingly interested in harnessing plants' native defense systems to provide natural protection against pathogens. We have found that one natural plant defense compound, jasmonic acid, not only protects against pathogenic bacteria, it also harms the plants ability to interact with beneficial bacteria. We are trying to identify the point at which jasmonic acid interferes with this beneficial interaction. Ultimately, this research could be helpful to Vermont farmers, especially organic farmers, as they try to increase interactions with beneficial bacteria and
reduce bacterial disease of plant crops.
Publications
- No publications reported this period
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Progress 10/01/05 to 09/30/06
Outputs
The objectives of this project are to examine the effect of jasmonic acid-inhibition of legume nodule formation on both gene expression and nodule development. In addition, we propose to examine the effect of co-inoculation of the beneficial soil bacteria Pseudomonas fluorescens and Sinorhizobium meliloti on legume nodulation. The beneficial effect of some P. fluorescens strains has been proposed to be due to stimulation of the plant defense response via the jasmonic acid signaling pathway. We will test whether or not P. fluorescens inhibits formation of nitrogen-fixing legume nodules. We have shown that jasmonic acid inhibits induction of a key plant gene that is a hallmark of the early nodulation response, RIP1. In addition, we demonstrated that jasmonic acid has a dose responsive effect on nodulation. Finally, in collaboration with Dr. Giles Oldroyd (John Innes Centre, UK), we showed that jasmonic acid interacts with the gaseous hormone, ethylene, in a complex
signaling network to regulate the response to Rhizobium bacteria. These results indicate that there are multiple points at which these two signaling pathways intersect, providing a mechanism for plants to continually assess biotic and abiotic conditions thereby use environmental inputs to regulate the formation of nitrogen-fixing nodules. In the next year of this project, we hope to examine the role of prior colonization by P. fluorescens on nodule formation.
Impacts
Plants produce chemicals that provide a defense against pathogenic bacteria. Organic gardeners are increasingly interested in harnessing plants' native defense systems to provide natural protection against pathogens. We have found that one natural plant defense compound, jasmonic acid, not only protects against disease-causing bacteria, it also harms the plants ability to interact with beneficial bacteria. We are trying to identify the point at which jasmonic acid interferes with this beneficial interaction. Ultimately, this research could be helpful to Vermont farmers, especially organic farmers, as they try to increase interactions with beneficial bacteria and reduce bacterial disease of plant crops.
Publications
- Jongho Sun, Vinitha Cardoza, David M. Mitchell, Lydia Bright, Giles Oldroyd and Jeanne M. Harris. (2006). Crosstalk between Jasmonic acid, ethylene and Nod factor signaling allows integration of diverse inputs for regulation of nodulation. The Plant Journal, 46: 961-970.
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