竹嵌紋病毒之分子生物學─子計畫四：竹嵌紋病毒缺失RNA之研究(2/3)
Date Issued
1999
Date
1999
Author(s)
DOI
882311B002007B11
Abstract
In order to study the defective RNAs (D RNAs) of Bamboo mosaic virus (BaMV), 35
cDNA clones were obtained from D RNA-containing BaMV virions, nine of them were
sequenced and proved to be BaMV D RNAs. A protoplast infection assay was used to
evaluate the biological activity of cloned D RNAs. By co-inoculating the RNA transcripts of
BaMV and D RNAs into tobacco protoplasts, the accumulation of D RNAs was analyzed after
- 2 -
24 hours. The results indicated that at least six clones of BaMV D RNAs were infectious but
none could interfere with the replication of BaMV. The D RNAs of Clover yellow mosaic
virus (ClYMV) were reported to contain a fusion open reading frame (ORF) of replicase and
coat protein genes, which was essential for their infectivity. On the contrary, D52 was the
only infectious clone of BaMV D RNAs containing the in-frame fusion ORF. Therefore, the
maintenance of the reading frame of coat protein gene in the fusion ORF was not required for
the amplification of BaMV D RNAs in vivo. To test whether the ORF of replicase gene is
important for the biological activity of BaMV D RNAs, two mutants were constructed from
D20, which had the highest level of accumulation than other clones in protoplast assay.
D20-pml was a mutant whose original start codon was destroyed. D20-spe was a frame-shift
mutant with only five amino acid residues translated. Both mutants could not maintain the
original ORF and were nonviable when assayed in tobacco protoplasts. The results
suggested that the maintenance of the replicase ORF is crucial for the accumulation of BaMV
D RNAs in vivo. From the above results, the characters of BaMV D RNAs are different
from those of ClYMV D RNAs. The significance and influence of ORF on BaMV D RNAs
needs further study.
Subjects
Bamboo Mosaic
BaMV
Defective RNA
Publisher
臺北市：國立臺灣大學植物病理與微生物學系暨研究所
Type
other
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