Histological and Cytological Changes in Leaves of Cherry Leaf Roll Virus (CLRV)-infected Birch, Ash, and Wild Cherry

1993

S. 183

Unselbständiges Werk

200077360

Infection of birch (Betula pendula) with cherry leaf roll virus is quite common in European forests. It has been transmitted experimentally to several American birches, including Betula alleghaniensis, Betula papyrifera and Betula occidentalis. It has recently been detected in declining wild cherry trees from a seed propagation nursery in North Rhine-Westfalia. European ash trees (Fraxinus excelsior) from several parts of Germany with virus-like symptoms have been shown by immunoelectron microscopy and DAS-ELISA to be infected with cherry leaf roll virus. Light- and electron microscopy of infected leaves showed quantitative but not qualitative differences in cytological alterations among woody hosts; in chlorotic areas of birch leaves, virus-containing tubules emerging from or passing through plasmodesmata were often present. In European ash, only paramural bodies and cell-wall-like protrusions occurred, without characteristic virus-containing tubular inclusions; the latter were infrequent in cherry leaves. Viroplasmas could be detected only in young leaves of infected birch. Reduction of cell size and intercellular spaces in birch and ash and delaved leaf development characterized chlorotic leaf tissue of all the tree species investigated, as did reduction in number of chloroplasts per leaf cell. These cytological alterations seem to be virus-specific compared with chlorosis caused by other stresses.