Grants and Contracts Details
Description
In natural ecosystems, many plants are able to grow on nutrient-poor soils, and they do so by living
together for mutual benefit with microorganisms, an example of a process called symbiosis. The
symbiosis between arbuscular mycorrhizal (AM) fungi and >80% of land plants and that between
rhizobia and legumes represent the two most important symbiotic interactions between plant roots and
microbes. In the AM symbiosis, the AM fungi assist the plant in assimilating phosphate, whereas in the
legume-rhizobia symbiosis, the rhizobia fix atmospheric nitrogen for use by the plant. The finding that
the two symbiosis share overlapping signaling pathways in legumes suggests that the evolutionary
younger nitrogen-fixing symbiosis has acquired functions from the ancient AM symbiosis. Most recently,
a number of legume genes required for nodulation and AM symbiosis were cloned from several legumes.
Interestingly, nearly all these genes are highly conserved across multiple plant taxa, and their putative
orthologs can be defined in non-legumes such as rice and Arabidopsis. This observation provides a
unique opportunity to investigate ortholog functionality across species and to address questions pertinent
to the evolution of AM and nodulation symbiosis in plants. The research proposed herein seeks to
elucidate the function of non-legume orthologs of legume genes required for nodulation and AM
symbiosis. Specific objectives are: (I) Characterization of the function of the putative rice orthologs of
legume genes required for nodulation and AM symbiosis using reverse genetics tools; (2)
Complementation of the legume mutants that are defective in nodulation and/or AM symbiosis using the
putative rice orthologs; and (3) Comparative transcript profiling of wild-type and mutant rice lines under
the infection of AM fungi using the Rice Affymetrix GeneChip.
Broader Impacts of the Proposed Research
The AM and rhizobial symbioses are of critical importance in sustainable agriculture, since growth
of land plants is often limited by the amounts of nitrogen and phosphate in the soil. An in-depth
understanding of the genetic and molecular mechanisms underlying both symbioses will help to improve
the efficiency of plants for acquisition of phosphorus and nitrogen from natural ecosystems. From an
evolutionary point of view, the proposed research will provide novel insights into the evolution of gene
functions and pathways leading to species- or family-specific phenotypes, and will also bridge the gap
between comparative plant genomics and comparative plant biology.
Education will be a major focus of this proposal. In addition to integrating the proposed research
with teaching, the PI will also serve as a mentor to graduate and undergraduate students and to
postdoctoral researchers who will conduct the proposed research. The students and postdocs will be
trained in the areas of plant comparative and functional genomics, molecular biology of plant-microbe
interactions, evolution, and bioinformatics. We will particularly encourage the participation of members
of under-represented undergraduates to join our group. Undergraduates will be recruited from university
organizations whose membership is specifically composed of women and minorities. Moreover, we will
contribute in a direct and substantive manner to high school education in Kentucky through a high school
student and teacher outreach program at the University of Kentucky.
Status | Finished |
---|---|
Effective start/end date | 7/1/07 → 12/31/11 |
Funding
- National Science Foundation: $480,000.00
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