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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

Determining the Role and Function of Plant Inducible Antisense RNA in the Epiphytic Fitness of Pseudomonas syringae pv. syringae

EPA Grant Number: F6D20958
Title: Determining the Role and Function of Plant Inducible Antisense RNA in the Epiphytic Fitness of Pseudomonas syringae pv. syringae
Investigators: Parangan, Audrey Gavino
Institution: University of California - Berkeley
EPA Project Officer: Boddie, Georgette
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $101,784
RFA: STAR Graduate Fellowships (2006)
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Microbiology



To identify how antisense regulatory RNA is involved in the epiphytic fitness of Pseudomonas syringae pv. syringae.

Microbial communities living on plant surfaces, epiphyte s, can have both deleterious and beneficial agricultural and environmental impacts. The study of these communities is important in the development of better methods to prevent disease and other damage to crops. The aerial portions of a plant, known as the phyllosphere, are inhospitable to many bacteria due to a variety of environmental stresses. Despite these stressful conditions, epiphytic bacterial colonists of the phyllosphere thrive since they have evolved mechanisms to adapt to such conditions. This is important for many plant pathogens since they need to survive on the phyllosphere before they can enter the plant and incite disease. The plant pathogenic bacteria Pseudomonas syringae is among the most important epiphytes since it occurs ubiquitously on a wide variety of plants and is the causal agent of disease and frost injury to frost sensitive plants. I am interested in studying the genes involved in the epiphytic fitness of P. syringae, specifically, those that are expressed only on plants and which apparently encode antisense regulatory RNA.


Bioinformatics, biochemical, molecular genetics, & microbial ecology assays.

Our lab has identified 10 putitive antisense transcripts which are induced when P. syringae is grown on the surface of its host, Phaseolus vulgarus. I hypothesize that these transcripts function as regulatory antisense RNA to quickly down-regulate genes that are required to be turned off when the bacteria are present on the phyllosphere. I want to identify the conditions and compounds on a plant surface that induce expression of these antisense transcripts using various bioassays. Additionally, bioinformatics and molecular genetic and biochemical tools will be used to identify genes that are targeted for regulation by these antisense transcripts and to determine the method which these antisense transcripts are regulated and function. Lastly I will determine the involvement of these antisense transcripts in the epiphytic fitness of P. syringae by generating various mutant strains and overexpressor strains and observer the change in their epiphytic fitness by measuring their growth rate on their host phyllosphere. These studies will allow for a better understanding of the mechanisms which contribute to the epiphytic fitness of P. syringae, which ultimately results in their pathogenesis. Although antisense RNA in bacteria were first discover about 20 years ago, researchers are only recently studying their importance in bacteria. This study will generate important information in this relatively new field of research as well as ultimately allow for the development of methods which offer a more environmentally sound and sustainable mean for disease control than the pesticide-dependent techniques implemented to date.

Expected Results:

An understanding of the gene regulation which allows for the epiphytic fitness of P. syringae. This will generate knowledge of how P. syringae is a successful pathogen.

Supplemental Keywords:

epiphytic fitness, antisense regulatory RNA, plant pathogenesis,, RFA, Scientific Discipline, Sustainable Industry/Business, Genetics, Sustainable Environment, Technology for Sustainable Environment, Environmental Microbiology, Biochemistry, bioengineering, genetic engineering, crop protection, agriculture, bioinformatics

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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