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Physiology and Biochemistry

Hypersensitive Resistance: Determination of Lignin in Leaves with a Localized Virus Infection. W. C. Kimmins, Professor, Department of Biology, Life Sciences, Dalhousie University, Halifax, Nova Scotia, Canada; D. Wuddah, Research Assistant, Department of Biology, Life Sciences, Dalhousie University, Halifax, Nova Scotia, Canada. Phytopathology 67:1012-1016. Accepted for publication 27 January 1977. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1012.

The amount of lignin in dwarf bean leaves infected with the necrotic lesion-inducing tobacco necrosis virus was determined every 24 hr for 120 hr following inoculation and compared with the lignin levels in abraded leaves and untreated leaves. The results from examining changes in absorption due to ionization, and the yields of lignothioglycolic acid and phenolic aldehyde derivatives showed that between 24 and 120 hr more lignin was present in virus-infected and abraded leaves than in untreated controls. The relative yields of phenolic aldehydes indicated that the lignin recovered from the three treatments was similar in structure. The amount of lignin in dwarf bean leaves with localized infections caused either by tobacco necrosis, tobacco mosaic, or southern bean mosaic viruses reached higher levels than in abraded tissue and was correlated with the size and number of necrotic lesions. Therefore in addition to abrasion, virus-induced necrosis also was associated with increased lignin and may have resulted from secondary injury to the tissue as infection progressed. It is concluded that lignin is a constituent of the secondary cell wall thickening induced by wounding and postulated to be a barrier to spread of the virus.