Submitted to: Molecular Plant Microbe International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2001
Publication Date: N/A
Technical Abstract: Double-stranded RNAs (dsRNA) are pandemic in plant pathogenic fungi, and frequently are found to affect virulence and other phenotypic characters of the fungi they infect. In preliminary studies, to determine if double-stranded RNA was present in Fusarium solani f. sp. glycines (F.s.g.), 24 isolates from field-grown soybeans were analyzed. A dsRNA extraction procedure was used on the mycelia of six-day old cultures grown in potato dextrose broth. Nucleic acids were separated from cell contents, and DNA was removed with DNAse I. The presence of dsRNA fragments was resolved in either 0.65% percent (%) agarose gels, run 24 hours at plus (+) 7 degrees (deg)C and 70 volts (V), or 0.80% gels, run 12 hours at + 22 deg C and 70 V. The ethidium bromide-stained bands were visualized in UV light. 15 of 24 isolates (62.5%) contained dsRNA. One isolate contained 3 fragments, of 1.9, 2.3 and 10.6 kilobase pairs (kb), 2 isolates contained 2 fragments (2.0 and 11.0 kb in one, and 2.4 and 11.0 kb in the other), 10 isolates contained a 10.6 to 13.0 kb fragment, and 2 isolates contained a fragment of 1.0 or 2.6 kb. We concluded that dsRNA is present in a high proportion of soybean-infecting isolates of F.s.g. We found significant variation in pathogenicity among isolates, and correlation between dsRNA presence and suppression of virulence.