Abstract
The location and structural characteristics of the membranous organelles in the cells of local lesion area produced by cucumber mosaic virus (CMV) in cowpea (Vigna sinensis (L.) Endl. var. sesquipedalis; Kurodane-sanjaku) leaves were investigated by electron microscopy and compared with those of healthy cells. In the healthy tissue the membranous organells were mainly observed in the vacuole of phloem and epidermal cells, with small and simple structure. In the cells dying due to the infection, on the other hand, tubular and circinate membrane aggregations developed between the cytoplasm and the cell wall and in the vacuole. When these cells had died completely, the remnants of the membranous organelles were seen in the electron-lucent areas in the vicinity of the cell wall and in the central part. In the cells surrounding the dead cells, enlarged and complex membranous organelles containing knots of anastomosing tubules appeared mainly in the vacuole. Considering the location and changes in structure of these membranous organelles, they are assumed to play a role in excretion and a mediative role between the vacuole and cell exterior. The organelles seemed to be formed owing to invagination of plasma membrane.
