Epiphytic bacteria and yeasts on apple blossoms and their potential as antagonists of Erwinia amylovora

P Lawrence Pusey; Virginia O Stockwell; Mark Mazzola

doi:10.1094/PHYTO-99-5-0571

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Epiphytic bacteria and yeasts on apple blossoms and their potential as antagonists of Erwinia amylovora

Journal article

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Epiphytic bacteria and yeasts on apple blossoms and their potential as antagonists of Erwinia amylovora

P Lawrence Pusey, Virginia O Stockwell and Mark Mazzola

Phytopathology, Vol.99(5), pp.571-581

05/2009

DOI: https://doi.org/10.1094/PHYTO-99-5-0571

Handle:

https://hdl.handle.net/2376/108608

PMID: 19351253

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Abstract

Erwinia amylovora - physiology

Oregon

Weather

Bacteria - isolation & purification

Environment

Flowers - microbiology

Malus - microbiology

Yeasts - isolation & purification

Malus - growth & development

Flowers - growth & development

Washington

Apple blossoms were sampled for indigenous epiphytic populations of culturable microorganisms during different stages of bloom at two locations in central Washington State and one site in Corvallis, OR. Frequencies and population sizes of bacteria on stigmas of apple were lower in Washington than at Corvallis, where average relative humidity was higher and possibly favored greater colonization; however, bacteria at Corvallis were mainly pseudomonads, whereas those in Washington were diverse, composed of several genera. In Washington, yeast as well as bacteria were isolated from both stigmatic and hypanthial surfaces. Sampled blossoms were processed immediately to assess microbial populations, or after a 24-h incubation at 28 degrees C and high relative humidity, which broadened the range of detectable taxa evaluated as potential antagonists. Identifications were based on fatty acid methyl ester profiles and rDNA sequence analyses. Yeasts or yeastlike organisms were detected at frequencies similar to or greater than bacteria, particularly in hypanthia. When microbial isolates were tested for their capacity to suppress Erwinia amylovora on stigmas of detached crab apple flowers, many were ineffective. The best antagonists were the bacteria Pantoea agglomerans and Pseudomonas spp. and a few yeasts identified as Cryptococcus spp. Further evaluation of these taxa on flowers could lead to the discovery of additional biocontrol agents for fire blight.

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Title: Epiphytic bacteria and yeasts on apple blossoms and their potential as antagonists of Erwinia amylovora
Creators: P Lawrence Pusey - U.S. Department of Agriculture, Agricultural Research Service, Tree Fruit Laboratory, Wenatchee, WA 98801, USA. larry.pusey@ars.usda.gov
Virginia O Stockwell
Mark Mazzola
Publication Details: Phytopathology, Vol.99(5), pp.571-581
Academic Unit: Plant Pathology, Department of
Publisher: United States
Identifiers: 99900547493301842
Language: English
Resource Type: Journal article