Occurrence of a DNA sequence of a non-retro RNA virus in a host plant genome and its expression: evidence for recombination between viral and host RNAs.
This study demonstrates that sequences homologous to those of the non-retro RNA virus (Potato virus Y; PVY) are integrated into the genome of several grapevine varieties. The integrated PVY-coat-protein-like cistron is expressed in the grapevine as indicated by Southern and Western blot analyses as well as by RNase protection assay. In addition, genome-walking studies showed that one PVY-like sequence is flanked by 41-bp direct repeats and is embedded in authentic grapevine sequences, flanked by inverted repeats. Rearranged PVY-like sequences were also found in tobacco. It is suggested that nonhomologous recombination of a potyviral RNA with RNA of a retrotransposable element took place at some point in evolution. The initial integration locus was probably within a grapevine gene homologous to a pentatricopeptide repeat-carrying protein, and was later transposed to other locations. The current location is reminiscent of a MITE-type retroelement, indicating transposition history. Because grapevine cultivars are propagated asexually, without going through a meiotic phase, the chance for DNA recombination is minimal and the foreign integrated sequence may be better conserved, enabling it to be expressed correctly in the recipient genome.
Tanne
Edna
E
Virus Laboratory, The Hebrew University of Jerusalem, Faculty of Agricultural, Food and Environmental Quality Sciences, Robert H. Smith Institute for Plant Sciences and Genetics, Rehovot 76100, Israel.
Sela
Ilan
I
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D004279:DNA, Viral / Q000032:analysis / Q000235:genetics*; D018745:Genome, Plant; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics / Q000821:virology*; D017800:Potyvirus / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D011995:Recombination, Genetic; D027843:Vitis / Q000821:virology
D017931:DNA Primers; D004279:DNA, Viral; D018749:RNA, Plant; D012367:RNA, Viral