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The overall goal of this project is to establish an integrated research and outreach activity to deal with management of the bacterial disease fire blight, caused by Erwinia amylovora, that attacks apples, pears, and other members of Rosaceae, and provide both short- and long-term solutions to dealing with this important disease using a multidisciplinary approach. <P>
Our short-term goal is to develop environmentally sound and effective methods of management and control for this disease, by capitalizing on 1) state of the art knowledge of the biology of the pathogen, host, antagonists, and inhibitors; and 2) on advances in nanotechnology for delivery of control agents. <P>
Our long-term goal is to incorporate genetic resistance into the host, apple, so that apple trees can fight off the pathogen on their own. This will capitalize on 1) expansive genomics resources available for the apple genome; and 2) genomics-based approaches for identifying and characterizing these genes. <P>
In the future, these isolated gene(s) can then be incorporated into apples using established genetic engineering technologies. Throughout, we will translate project outcomes to beneficiaries of this research, namely growers and consumers, through effective and innovative outreach and educational programs and we will address the economic benefits and available marketing tools to support adoption of the end products of this integrated genomics and management systems project. <P>
The following specific objectives will be pursued:<OL> <LI> Evaluate and assess virulence inhibitors against Erwinia amylovora.<LI> Evaluate and enhance efficacy of microbial biocontrol agents. <LI> Controlled and sustained delivery of virulence inhibitors and biocontrol agents mediated by microparticles/nanoparticles. <LI> Identify and clone fire blight resistance genes. <LI> Develop and deliver outreach programs in conjunction with economic and marketing studies for adoption of comprehensive management systems for fire blight control.
NON-TECHNICAL SUMMARY: This project will focus on the disease fire blight, caused by the bacterium Erwinia amylovora. This disease attacks various fruit crops including apples and pears, among others. This disease alone results in significant losses and contributes to production costs exceeding $100 million annually. Current antiquated control methods, usage of the antibiotic streptomycin, are ineffective. We will address this threatening disease by pursuing a dual strategy having short- and long-term impacts. For the short-term, we will identify and/or evaluate promising virulence inhibitors and antagonistic microbial agents against the bacterium E. amylovora by exploiting knowledge of the biology of the pathogen, host, antagonists, and inhibitors. We will deliver these biocontrol agents using biocompatible and environmentally-safe nanoparticles. For the long-term, we will capitalize on expansive apple genomics resources, and utilize genomics-based approaches to identify and characterize genes for resistance to fire blight. This research activity will be accompanied with a vigorous outreach program that will develop and deliver knowledge-based information, demonstration plots, and web-based educational modules on biocontrol, nanotechnology, and genomics. We will conduct economic studies on benefits and marketing strategies, and deliver this knowledge to the industry.
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APPROACH: In this project, we will use agents, both chemical inhibitors (small molecular inhibitors) and microbial antagonists, that will inhibit the type III expression or effector secretion and translocation of the bacterium Erwinia amylovora to control this bacterium. We plan to deliver these promising biocontrol agents and potential virulence inhibitors using a novel delivery system. This delivery system consists of nanoparticles of biodegradable materials of precise controlled size, size distribution, and shell thickness coated with either these virulence inhibitors or biocontrol agents for the purpose of targeted and effective control of Erwinia amylovora in apple blossoms and shoots. We will design models for controlled release of these agents, select biocompatible materials, and implement a proof-of principle prototype for delivery of these control agents on apple tissues. For our long term management strategy for fire blight, we intend to identify and characterize gene(s) for resistance to fire blight. We will focus quantitative trait loci (QTL) for fire blight resistance identified in the apple. We will map this QTL using our apple mapping population (of approximately 120 individuals), and saturate the QTL region with molecular markers including SSRs and SNPs from our vast genomics resources. We will used our genome-wide physical map of the apple to locate the BAC contig covering this locus, and proceed to use a map-based cloning approach to clone this major QTL. We will also sequence this BAC contig, identify candidate genes for resistance, and pursue functional studies to identify functional genes for resistance to fire blight. The two research efforts undertaken in this project will be accompanied by an educational and outreach effort. Outreach efforts will address concerns, provide demonstrations, and develop web-based educational programs that will enhance the public and industry understanding and appreciation of the technologies used in this project. In addition to determining the optimal technology adoption path, it is also important to measure the economic benefits or welfare effects, individual and societal, for production and consumption of apples grown under integrated and effective management systems.