title: MicroRNAs, the epigenetic memory and climatic adaptation in Norway spruce.
abstract: *Norway spruce expresses a temperature-dependent epigenetic memory from the time of embryo development, which thereafter influences the timing bud phenology. MicroRNAs (miRNAs)are endogenous small RNAs, exerting epigenetic gene regulatory impacts. We have tested for their presence and differential expression. *We prepared concatemerized small RNA libraries from seedlings of two full-sib families, originated from seeds developed in a cold and warm environment. One family expressed distinct epigenetic effects while the other not. We used available plant miRNA query sequences to search for conserved miRNAs and from the sequencing we found novel ones; the miRNAs were monitored using relative real time-PCR. *Sequencing identified 24 novel and four conserved miRNAs. Further screening of the conserved miRNAs confirmed the presence of 16 additional miRNAs. Most of the miRNAs were targeted to unknown genes. The expression of seven conserved and nine novel miRNAs showed significant differences in transcript levels in the full-sib family showing distinct epigenetic difference in bud set, but not in the nonresponding full-sib family. Putative miRNA targets were studied. *Norway spruce contains a set of conserved miRNAs as well as a large proportion of novel nonconserved miRNAs. The differentially expression of specific miRNAs indicate their putative participation in the epigenetic regulation.
authors.affiliation: Norwegian Forest and Landscape Institute, PO Box 115, N-1431 Ås, Norway.
authors.forename: Igor A
authors.initials: IA
authors.lastname: Yakovlev
authors.affiliation: Norwegian Forest and Landscape Institute, PO Box 115, N-1431 Ås, Norway.
authors.forename: Carl Gunnar
authors.initials: CG
authors.lastname: Fossdal
authors.affiliation: University of Life Sciences, Department of Plant and Environmental Sciences, PO Box 5003, N-1432 Ås, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Johnsen
mesh_terms: D000220:Adaptation, Biological; D001483:Base Sequence; D002980:Climate; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018519:Meristem / Q000254:growth & development; D035683:MicroRNAs / Q000378:metabolism*; D028222:Picea / Q000235:genetics* / Q000502:physiology; D018749:RNA, Plant / Q000378:metabolism*; D017423:Sequence Analysis, RNA; D013696:Temperature
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant