The Distribution and Ultrastructural Effects of Passionfruit Woodiness Virus in Bean Leaves

Abstract

An electron microscope examination was made of mesophyll cells in the leaves of French bean (Phaseolus vulgaris L.) cv. Cherokee Wax infected with passionfruit woodiness virus (PWV). Virus particles and virus-induced inclusions were found in the mesophyll cells of yellow areas of inoculated leaves, leaves with vein clearing, and yellow areas of leaves with systemic mosaic symptoms, but not in the green areas of inoculated leaves and only occasionally in dark green areas of leaves with systemic mosaic symptoms. Virus-induced inclusions were confined to the cytoplasm and were frequently associated with cell membranes. Chloroplasts in infected cells had an increased tendency to invagination of the limiting membranes, and the invaginated portion frequently contained a mitochondrion. Some effects were recorded on the numbers of starch grains per chloroplast.