title: Inducible Transposition of a Heat-Activated Retrotransposon in Tissue Culture.
abstract: A transposition of a heat-activated retrotransposon named ONSEN required compromise of a small RNA-mediated epigenetic regulation that includes RNA-directed DNA methylation (RdDM) machinery after heat treatment. In the current study, we analyzed the transcriptional and transpositional activation of ONSEN to better understand the underlying molecular mechanism involved in the maintenance and/or induction of transposon activation in plant tissue culture. We found the transposition of heat-primed ONSEN during tissue culture independently of RdDM mutation. The heat activation of ONSEN transcripts was not significantly up-regulated in tissue culture compared with that in heat-stressed seedlings, indicating that the transposition of ONSEN was regulated independently of the transcript level. RdDM-related genes were up-regulated by heat stress in both tissue culture and seedlings. The level of DNA methylation of ONSEN did not show any change in tissue culture, and the amount of ONSEN-derived small RNAs was not affected by heat stress. The results indicated that the transposition of ONSEN was regulated by an alternative mechanism in addition to the RdDM-mediated epigenetic regulation in tissue culture. We applied the tissue culture-induced transposition of ONSEN to Japanese radish, an important breeding species of the family Brassicaceae. Several new insertions were detected in a regenerated plant derived from heat-stressed tissues and its self-fertilized progeny, revealing the possibility of molecular breeding without genetic modification.
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Masuta
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Nozawa
authors.affiliation: Ishikawa Prefectural University, Nonoichi, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takagi
authors.affiliation: Iwate Biotechnology Research Center, Kitakami, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yaegashi
authors.affiliation: NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Center for Ecological Research, Kyoto University, Otsu, Japan.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Ito
authors.affiliation: Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saito
authors.affiliation: NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo, Japan.
authors.forename: Hisato
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Matsunaga
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Masuda
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kato
authors.affiliation: Faculty of Science, Hokkaido University, Sappor, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Ito
mesh_terms: D019607:Brassicaceae / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D006358:Hot Temperature; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D046509:Tissue Culture Techniques
chemical_list: D010940:Plant Proteins; D018626:Retroelements
keywords: Brassicaceae; Heat stress; ONSEN; Tissue culture; Transposon