Ultrastructural features of Phytophthora ramorum and infection morphology on leaves
E. R. Florance1 and J. L. Parke2
The anatomy and infection morphology of Phytophthora ramorum on leaves of various species were analyzed using light and scanning electron microscopy. Leaves of Umbellularia californica, Rhododendron macrophyllum, Vaccinium ovatum were inoculated under controlled conditions using zoospore suspensions. Horticultural cultivars of Rhododendron and Vaccinium were also included in the assay. Leaf tissue was harvested at various time intervals to study the sequence of infection events. Samples were fixed in 4% glutaraldehyde followed by 1% osmium tetroxide and prepared for microscopic analysis. Hyphal growth appeared more abundant on the ventral than on the dorsal surface of leaves, and preliminary analysis indicates that stomata are one portal of entry to the interior tissues. Hyphae, sporangia, and chlamydospores were more abundant on Umbellularia californica than on other hosts in this assay.
1Dept. of Biology, Lewis and Clark College, Portland, OR 97219
2Dept. of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331
|
