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Research Detection of dsRNA from Cleistothecia and Conidia of the Grape Powdery Mildew
Pathogen, Uncinula necator. Ossmat I. Azzam, Graduate Research
Assistant, and Dennis Gonsalves, Professor, Department of Plant Pathology, Cornell University, New York State
Agricultural Experiment Station, Geneva 14456. Plant Dis. 75:964-967. Accepted for
publication 11 February 1991. Copyright 1991 The American Phytopathological
Society. DOI: 10.1094/PD-75-0964. Double-stranded RNA species ranging in molecular weight from 0.95 to 6.3 ×
106 were detected in grapevines in New York. We recently showed that
two of the species (Mr = 5.3 and 4.4 × 106) are
associated with rupestris stem pitting disease. In this report, we show that the
other eight detectable dsRNA species are associated with the powdery mildew
fungus, Uncinula necator. These dsRNAs associated with the powdery mildew
fungus were previously detected in leaves and epidermal stem tissue of
grapevines infected with powdery mildew. The same dsRNA species were also
detected from extracts of isolated cleistothecia and conidia of U. necator
devoid of plant tissue. Isometric and rigid rodlike particles were observed in
single cleistothecia preparations when examined under transmission electron
microscopy. |