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Research Detection of Pseudomonas syringae pv. morsprunorum on Cherries
in Michigan with a DNA Hybridization Probe. J. M. Paterson and A. L. Jones, Department of
Botany and Plant Pathology and The Pesticide Research Center, Michigan State
University, East Lansing 48824. Plant Dis. 75:893-896. Accepted for publication 4 March 1991.
Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0893. A PST-DNA probe, developed for differentiating Pseudomonas syringae
pv. tomato from P. s. pv. syringae, hybridized with DNA
extracted from P. s. pv. morsprunorum but weakly or not at all
with DNA extracted from P. s. syringae. Purified DNA and DNA from colony
blots of 18 strains of P. s. morsprunorum, including strains from
England, Poland, South Africa, and the United States, hybridized with the
radiolabeled probe, whereas 19 of 20 strains of P. s. syringae isolated
from deciduous tree fruit crops did not hybridize or weakly hybridized with the
probe. The detection limit for bacteria from pure culture was approximately 2.2
× 104 colony-forming units (cfu) per milliliter. DNA from P. s.
morsprunorum extracted from lesions on fruit was detected by the probe, but
DNA from lesions on leaves was not detected. The number of bacteria was 100-fold
lower in effluent from leaves than from fruit. With field samples,
identifications made with the probe were in general agreement with those made by
standard biochemical and physiological techniques. EcoRI fragments of
P. s. morsprunorum DNA exhibited restriction fragment length polymorphism
when Southern blots were probed with the PST-DNA probe. The PST-DNA probe should
aid in the rapid detection of P. s. morsprunorum. |