title: Spaceflight induces both transient and heritable alterations in DNA methylation and gene expression in rice (Oryza sativa L.).
abstract: Spaceflight represents a complex environmental condition in which several interacting factors such as cosmic radiation, microgravity and space magnetic fields are involved, which may provoke stress responses and jeopardize genome integrity. Given the inherent property of epigenetic modifications to respond to intrinsic as well as external perturbations, it is conceivable that epigenetic markers like DNA methylation may undergo alterations in response to spaceflight. We report here that extensive alteration in both DNA methylation and gene expression occurred in rice plants subjected to a spaceflight, as revealed by a set of characterized sequences including 6 transposable elements (TEs) and 11 cellular genes. We found that several features characterize the alterations: (1) All detected alterations are hypermethylation events; (2) whereas alteration in both CG and CNG methylation occurred in the TEs, only alteration in CNG methylation occurred in the cellular genes; (3) alteration in expression includes both up- and down-regulations, which did not show a general correlation with alteration in methylation; (4) altered methylation patterns in both TEs and cellular genes are heritable to progenies at variable frequencies; however, stochastic reversion to wild-type patterns and further de novo changes in progenies are also apparent; and (5) the altered expression states in both TEs and cellular genes are also heritable to selfed progenies but with markedly lower transmission frequencies than altered DNA methylation states. Furthermore, we found that a set of genes encoding for the various putative DNA methyltransferases, 5-methylcytosine DNA glycosylases, the SWI/SNF chromatin remodeller (DDM1) and siRNA-related proteins are extremely sensitive to perturbation by spaceflight, which might be an underlying cause for the altered methylation patterns in the space-flown plants. We discuss implications of spaceflight-induced epigenetic variations with regard to health safety issues of spaceship crews and potentiality of spaceflight as a means for mutagenesis in crop breeding.
authors.affiliation: Key Laboratory of Molecular Epigenetic of MOE and Institute of Genetics & Cytology, Northeast Normal University, Changchun 130024, China.
authors.forename: Xiufang
authors.initials: X
authors.lastname: Ou
authors.forename: Likun
authors.initials: L
authors.lastname: Long
authors.forename: Yunhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Xue
authors.forename: Jingchun
authors.initials: J
authors.lastname: Liu
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Lin
authors.forename: Bao
authors.initials: B
authors.lastname: Liu
mesh_terms: D044503:5-Methylcytosine / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004251:DNA Transposable Elements / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D040582:Inheritance Patterns / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013026:Space Flight
chemical_list: D004251:DNA Transposable Elements; D010940:Plant Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044503:5-Methylcytosine; D004248:DNA (Cytosine-5-)-Methyltransferases; D045647:DNA Glycosylases