Sugarcane white leaf phytoplasma in tissue culture: long-term maintenance, transmission, and oxytetracycline remission.
Sugarcane white leaf (SCWL)-diseased sugarcane plants collected from Udornthani Province, in north-eastern Thailand, were the source for tissue culture experiments. Explants from axillary buds, meristem tips, and leaves grew optimally in Murashige-Skoog medium containing 0.5 mg/l alpha-naphthaleneacetic acid, 0.5 mg/l 6-benzylaminopurine, and 15% coconut water. Callus development and shoot/root proliferation were more rapid in cultures from diseased than from healthy plants. Disease symptoms continued for 6 years after culture initiation, and SCWL phytoplasma persisted, as confirmed by polymerase chain reaction using both 16S rDNA and 16S-23S rDNA primers. Phytoplasmas in the cultured plantlets were transmissible by grafting to sugarcane and periwinkle, and by feeding of the leafhopper vector Matsumuratettix hiroglyphicus to sugarcane. Although 50% of the plantlets were killed by oxytetracycline at 500 mg/ml, 70-100% of plantlets grown with 200-500 mg/ml oxytetracycline showed symptom remission through 5-8 subcultures. Typical phytoplasma-like bodies, visible by electron microscopy in sieve tubes of untreated diseased plantlets, were absent in antibiotic-treated plantlets. Thus, tissue culture provides a convenient and reliable in vivo system for investigation of SCWL phytoplasma.
Department of Plant Pathology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, 40002, Thailand. porwon@kku.ac.th
Porntip
P
Wongkaew
Jacqueline
J
Fletcher
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D030008:Catharanthus / Q000382:microbiology; D004199:Disease Vectors; D006430:Hemiptera / Q000382:microbiology; D010118:Oxytetracycline / Q000494:pharmacology*; D045582:Phytoplasma / Q000187:drug effects* / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology / Q000502:physiology / Q000648:ultrastructure; D031786:Saccharum / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology; D046509:Tissue Culture Techniques
D000900:Anti-Bacterial Agents; D010118:Oxytetracycline