Ultrastructural studies on bean leaf tissues infected with two strains of bean rugose mosaic virus

Abstract

Electron microscopic studies of bean plant tissues (Phaseolus vulgaris L.) infected with races A, or A, of bean pod mottle mosaic virus (BRMV), isolated in Guatemala, showed conspicuous differences in their intracellular behavior with bean pod mottle virus (BPMV) and cowpea mosaic virus (CPMV) although they were serologically unrelated to these viruses.

In infected cells, race A induced the appearance of huge live crystals. A second type of crystalline inclusion, of unknown nature, was found in some cells affected by this race. Finger-like growth in the cell wall and layered inclusions in the stroma of chloroplasts were also found associated with infection by race A of BRMV. The most conspicuous change caused by race A was an intense vesicularization of the cytoplasm. Virus-like particles were seen intercalated or within these cytoplasmic vesicles, some of which contained filamentous material. Particles were noted within the xylem and phloem vessels. Discrete aggregates of fibrous material appeared in the cytoplasm of some pavenchyma cells

The cellular changes observed in tissues infected with A. vaza are very similar to those previously described as associated with infection by the bean line pattern mosaic virus (BLPMV) and southern bean mosaic virus, cowpea strain (C-SBMV). Furthermore, the cytopathological effects and localization of A. vaza are quite similar to those of bean pod mottle virus and, to a lesser extent, cowpea mosaic virus.