@article{mbs:/content/journal/micro/10.1099/00221287-148-5-1389, author = "Nishigawa, Hisashi and Oshima, Kenro and Kakizawa, Shigeyuki and Jung, Hee-young and Kuboyama, Tsutomu and Miyata, Shin-ichi and Ugaki, Masashi and Namba, Shigetou", title = "Evidence of intermolecular recombination between extrachromosomal DNAs in phytoplasma: a trigger for the biological diversity of phytoplasma?bbThe GenBank accession numbers for EcOYW and EcOYM are AB076262 and AB076263, respectively.", journal= "Microbiology", year = "2002", volume = "148", number = "5", pages = "1389-1396", doi = "https://doi.org/10.1099/00221287-148-5-1389", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-148-5-1389", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "OY-W, wild-type onion yellows phytoplasma", keywords = "recombination", keywords = "OY-M, mild-symptom line of onion yellows phytoplasma", keywords = "phytoplasma", keywords = "OY, onion yellows", keywords = "extrachromosomal DNA", keywords = "EC-DNA, extrachromosomal DNA", keywords = "rolling circle replication", abstract = "Recombination among bacterial extrachromosomal DNAs (EC-DNAs) plays a major evolutionary role by creating genetic diversity, and provides the potential for rapid adaptation to new environmental conditions. Previously, a 7 kbp EC-DNA, EcOYW1, with a geminivirus-like rolling-circle-replication protein (Rep) gene was isolated and characterized from an original wild-type line (OY-W) of onion yellows (OY) phytoplasma, an endocellular cell-wall-less prokaryote that inhabits the cytoplasm of both plant and insect cells. EcOYW1, found in OY-W, was not present in a mild-symptom line (OY-M) derived from OY-W. A 4 kbp EC-DNA, pOYW, was also isolated and characterized from OY-W, and its pLS1-plasmid-like rep gene was expressed. This paper describes the isolation and sequencing of an EC-DNA of 5560 nt, EcOYW2, from OY-W, and its counterpart EC-DNA of 5025 nt, EcOYM, from OY-M. EcOYW2 and EcOYM contained seven and six ORFs, respectively. They both encoded a geminivirus-like Rep and a putative single-stranded-DNA-binding protein (SSB). Southern blot analysis indicated that no more EC-DNAs with a rep gene exist in either OY-W or OY-M, which means that the complete set of EC-DNAs has been cloned from the OY-W and OY-M lines of OY phytoplasmas. Sequence analysis revealed that both EcOYW2 and EcOYM have chimeric structures of previously characterized EcOYW1 and pOYW, suggesting that they have a recombinational origin. This is the first evidence of intermolecular recombination between EC-DNAs in phytoplasma. The possible implications of these findings in increasing the biological diversity of phytoplasma are discussed.", }