Minority Postdoctoral Research Fellowship for FY2006

Roberts Elizabeth L, San Mateo CA

Investigators

Abstract

This project is awarded under the Minority Postdoctoral Research Fellowships and Supporting Activities Program for 2006. AN INVESTIGATION OF SYMBIOTIC RELATIONSHIPS AND NUTRIENT ACQUISITION STRATEGIES OF ENDOPHYTIC FUNGI AND BACTERIA This investigation will utilize reporter gene technology to visualize interactions between bacteria and fungi that live inside of plant tissue (endophytes). Thus, fluorescent proteins will be inserted into the endophytic fungus Balansia epichloe and the endophytic bacterium Erwinia herbicola. The microbes will then be inoculated into leaves of Panicum sp. and fluorescent microscopy will be used to visualize where the microbes reside in the plant tissue and to determine whether they associate with each other. Next, to determine whether the association between the microbes is beneficial to one or both of them by increasing nutrient availability, the microbes will be used as microscopic biosensors of sugars in the intercellular spaces of Panicum leaves. A fungal biosensor of sugar will be made by fusing a fungal sugar-responsive gene to green fluorescent protein (gfp) on a plasmid and inserted into B. epichloe via Agrobacterium-mediated transformation. The constructed plasmid will bring about the accumulation of gfp fluorescence in response to sugar consumption. Intensity of fluorescence will be used to quantify the amount of available sugar. The fungal biosensor and previously constructed bacterial biosensors will be inoculated into Panicum sp. together and separately, and sugar availability in each situation will be compared. An additional study to determine whether auxin production by Balansia epichloe increases sugar availability in the intercellular spaces of Panicum sp. will be conducted. Auxin deficient mutants will be made by the process of plasmid insertion mutagenesis and compared to wild-type auxin producing strains of B. epichloe. Increased sugar availability as a result of auxin will be determined by comparing fluorescence intensity visualized in E. herbicola biosensors in Panicum infected with auxin deficient mutants and auxin producing B. epichloe. In order to successfully conduct the proposed investigation, proficiency in a number of [molecular genetic] experimental techniques will be acquired. During the tenure of this fellowship Dr. Roberts will get well versed in molecular biology, under the mentorship of Dr. Steven Lindow at University of California, Berkeley. Specifically for this study, she will learn and become adept at constructing plasmids with reporter genes, mutagenesis, and Agrobacterium tumefaciens-mediated transformation. Acquisition of these skills will further enhance her previous plant microbe research experience, which focused on general research techniques. As a well-rounded researcher she will be better equipped to start an active research program in plant-microbe interactions where she plans to encourage undergraduates to attain laboratory experience. She also wants to serve as a mentor to students interested in pursuing scientific careers. Moreover, she aspires to be an accomplished member of the scientific community by sharing knowledge gained through her research program.