|Abstract or Summary
- Cultivated lilies include many garden varieties in addition to
the Easter lily, Lilium longiflorum Thunb. A popular member of
the garden group is Lilium speciosum Thunb., whose leaves can be
discolored by a virus symptom described as streak mottle. This
disorder is characterized by dashes of chlorotic tissue interspersed
In order to gain further insight about the nature of the virus
inciting streak mottle on L. speciosum, leaf pieces of approximately
0.5 mm square were immersed in buffered glutaraldehyde fixative,
treated with osmium tetroxide, dehydrated, and embedded in epoxy
resin. After thin sectioning and staining, the specimens were examined
with an electron microscope.
Configurations described as pinwheels and bundles, characteristic
of 750 mμ flexuous rod viruses, were seen in abundance within
leaf mesophyll cells, epidermal cells, and to a lesser extent, in xylem cells. In agreement with previous workers, the pinwheel and
bundle inclusions were found to be different views of the same body.
This intracellular body associated with streak mottle can be described
as a cylindrical inclusion with curved plates emanating from a central
hollow core. While some viruses appear to occur along the inner
curvature of the plates, at least one has been reported as separate
from the pinwheel-bundle figure. It appears that streak mottle virus
is also one of the latter.
L. speciosum mesophyll cells were found to contain crystals,
and these were observed in both diseased and healthy tissue. Diseased
tissue displayed an additional crystalline body, which occurred
in clusters and was often seen in close proximity to pinwheel-bundle
figures. These bodies seem to be homologous to those found within
nuclei of tobacco leaf mesophyll cells infected with tobacco etch
virus, also a flexuous 750 mμ rod.
The chloroplasts of both infected and healthy mesophyll cells
showed large vacuoles of unknown significance. A smaller peripheral
vesicle that occurs between the two layered plastid-limiting membrane
seemed to occur more frequently in diseased cells than in
healthy. Depletion of a chloroplast substance is suggested by the
presence of these vesicles.
The remainder of the organelles, namely, dictyosomes, nuclei,
and mitochondria, appeared to be similar in both healthy and diseased cells.
On the basis of preliminary findings further work may establish
that streak mottle virus induces premature degeneration of host