Fine structure of tissue bordering lesions induced by wounding and virus infection

Abstract

Tissue in Phaseolus vulgaris L. cv. Pinto bean bordering local lesions induced by tobacco mosaic virus showed cell wall deposition associated with paramural body formation in a narrow ring of viable cells extending one to three cell diameters around the lesions. Deposition, which led to secondary cell wall thickening, was greatest 3–4 days after inoculation, the time when the lesion stopped expanding. Secondary cell wall thickening, of similar appearance but less pronounced, was seen in tissue bordering local lesions which continued to expand; no significant secondary cell wall thickening was observed in leaves with a nonlocalized infection. Cells bordering mechanical lesions differed markedly in fine structure from cells bordering virus and chemical lesions. It is suggested that the deposition of extra cell wall material in the wall regions of cells bordering fully expanded local lesions is associated with virus localization.