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United States Department of Agriculture

Agricultural Research Service

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Research Project: Host Specificity and Gene Flow of Fungicide Resistance Alleles Among Botrytis Cinerea Populations Infecting Small Fruit in the US Pacific Northwest

Location: Horticultural Crops Research

Project Number: 2072-22000-041-05-G
Project Type: Grant

Start Date: Sep 9, 2014
End Date: Sep 30, 2017

The objective of this project is to improve management of Botrytis fruit rot of berries. Despite intensive fungicide application programs aimed at control of this disease in the US Pacific Northwest (US-PNW), it is estimated that fruit losses and downgrades in fruit quality exceed 25% of the harvestable fruit due to incomplete disease control. Additionally, fungicides used for control have lost effectiveness due to the development of resistance, further limiting management options. Specific outcomes of this project will include a study of host specificity and gene flow among populations of Botrytis cinerea infecting raspberry, blueberry and strawberry. Simultaneously, we will characterize resistance mutations to several fungicides currently used to Botrytis fruit rot control where molecular mechanisms of resistance are known. Integrating these two approaches will allow inferences about the host specificity of B. cinerea populations and the extent of pathogen and resistance gene movement (migration = gene flow) among populations. Specific questions of interest will be: Are pathogen populations different among different berry crops? Can pathogens and fungicide resistance genes move from crop to crop? Is fungicide resistance ubiquitous or only detected in some populations on some crops? Answers to these questions are critical for the design of rational strategies to mitigate the effects of fungicide resistance development and the deployment of such strategies in small fruit on a regional basis.

Botrytis cinerea will be sampled from commercial raspberry, blueberry, and strawberry fields in the US Pacific Northwest. Five locations per host (15 locations total) will be sampled and 30 isolates will be obtained per location, per host. Samples will be surface disinfested and placed in moist chambers to induce sporulation and/or plated on agar media containing antibiotics to isolate the pathogen. Colonies emerging from tissues will be identified using morphological and molecular methods and placed in long-term storage for further study. Isolates will be scored for genetic variation at 15 microsatellite (SSR) loci previously developed for B. cinerea using PCR conditions and relevant methodology. Sampled isolates will be screened for resistance to currently registered fungicides in small fruit production in the US Pacific Northwest. Amendment #3 adds funds to continue the current research objectives and will be used to complete SSR analysis and fungicide resistance research, as well as perform data analysis and prepare research for publication.

Last Modified: 09/25/2017
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