Complexity of dsRNA mycovirus isolated from Fusarium graminearum.
Fusarium graminearum is the causal agent of a serious scab disease of small grains in Korea. We screened 827 isolates of F. graminearum from diseased barley and maize and tested for the presence of double-stranded RNA (dsRNA) mycovirus. Of them, 19 isolates contained various sizes of dsRNAs. A dsRNA associated with pronounced morphological changes including reduction in mycelial growth, increase in dark orange to red pigmentation, reduced sporulation and virulence was previously observed in nine dsRNA-containing Fusarium isolates (Chu et al., Appl Env Microbiol 68, 2529-2534, 2002). Ten additional isolates were found infected with dsRNA mycoviruses. These mycoviruses contain 2-4 different segments of dsRNAs with the size-range of approximately 1.7-10 kbp in length. The presence of dsRNAs did not affect colony morphology and were transmissible through conidia and ascospore with incidence of 30-100%. Interestingly, dsRNA mycovirus found in F. graminearum isolates, JB33 and JNKY19, that show the pattern of mixed infection of two different viruses were transmitted to all progeny conidia and ascospores. These results indicate that there is genomic diversity of dsRNA mycoviruses that infect F. graminearum isolates and that impact of virus infection on host's morphology and virulence is determined by the interaction between dsRNAs and the fungal host, not by the mere presence of the dsRNAs.
Chu
Yeon-Mee
YM
School of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea.
Lim
Won-Seok
WS
Yea
Sang-Jin
SJ
Cho
Jeom-Deog
JD
Lee
Yin-Won
YW
Kim
Kook-Hyung
KH
D000595:Amino Acid Sequence; D005670:Fusarium / Q000378:metabolism / Q000821:virology*; D008969:Molecular Sequence Data; D010641:Phenotype; D017434:Protein Structure, Tertiary; D012328:RNA Viruses / Q000235:genetics*; D012330:RNA, Double-Stranded
D012330:RNA, Double-Stranded