Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/25/2009
Publication Date: 3/25/2009
Citation: Eskandari, F., Bruckart, W.L. 2009. Greenhouse germination and characterization of Synchytrium solstitiale resting spores. Phytopathology. 99(6, Supplement): S203. Interpretive Summary:
Technical Abstract: Synchytrium solstitiale was evaluated for suitability in biological control of yellow starthisle (YST). A protocol was developed for maintenance of S. solstitiale in galled tissue under greenhouse conditions. Recently, protocol has been developed for germination of resting spores. Resting spores mature in large numbers 7 to 10 days after galls develop, and they are distinct morphologically. For this reason, S. solstitiale is considered a long-cycled chytrid and it is described as diheterogallic. Resting spores are dark, single-celled, and embedded within leaf and petiole tissues. Leaves containing resting spores were dried and stored for two months. Leaves were surface sterilized for 10 minutes in 10 percent bleach and rinsed for 10 minutes each in three changes of sterile distilled water (SDW). Resting spores were scraped out of plant tissue, placed on 2 percent water agar (WA) in small Petri dishes, which were wrapped in aluminum foil and incubated at 10 (night) and 15 (day) centigrade. After 10 – 25 days, some resting spores germinated and formed a round yellow-orange vesicle on the outside. Further development of the vesicle occurred only after individual germinated resting spores were picked off of the WA and placed in SDW with streptomycin (100 ppm) in the well of a hanging-drop slide. Prepared slides were placed in a moist chamber and incubated under conditions described above. The opaque orange vesicles changed to a translucent pink in 2 to 24 hours, and movement of zoospores was seen after that development. The vesicle ruptured and zoospores were released in a manner similar to that of release from sori in galls. YST inoculated with germinated resting spores at the orange vesicle stage became infected following the same protocol for inoculating YST with galled leaf material. These results prove the viability of resting spores and suggest they are a functional part of the S. solstitiale life cycle. Characterization of resting spore germination should facilitate taxonomic characterization of S. solstitiale.