ARS | Publication request: Quantifying Symptom Severity in Wheat Infected with Wheat Streak Mosaic Virus Using Both Visual and Digital Means of Assessment

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2004
Publication Date: June 1, 2004
Citation: Van Winkle, D.H., French, R.C., Stenger, D.C. 2004. Quantifying symptom severity in wheat infected with wheat streak mosaic virus using both visual and digital means of assessment. American Phytopathological Society Astracts. Phytopathology 94:S99.

Technical Abstract: Five symptom attributes (mean latent period, leaf area, relative chlorosis, relative necrosis, and mean chlorotic density) of Wheat streak mosaic virus (WSMV) infection of wheat were evaluated. Seedlings of four wheat cultivars were mechanically inoculated with WSMV strains Sidney 81 (S81) or El Batán 3 (EB3). Mock-inoculated plants served as negative controls. For all cultivars, mosaic symptoms were first apparent in plants inoculated with S81. Mean latent period (time to onset of observable mosaic) differed among cultivars for both strains, with Arapahoe<Bobwhite<Michigan Amber<Tomahawk. At 14 days post inoculation, the two youngest, fully-expanded leaves (nodes 3 & 4 or 4 & 5) of each plant were digitally imaged and analyzed using Image-Pro Plus (version 4.5, Media Cybernetics') software configured in accordance with user-defined parameters. Mean chlorotic density, relative chlorosis, and relative necrosis were significantly greater for plants infected with EB3 compared to S81. Bobwhite and Tomahawk plants infected with either strain exhibited more necrosis and chlorosis than did infected Arapahoe or Michigan Amber plants. Mean leaf area was lower for WSMV-infected plants compared to controls but there was no significant difference between the two virus strains. Collectively, these results indicate that measurements of virulence based on timing of disease symptom onset may not be correlated with other measures of disease severity.