Spaceflight-induced genetic and epigenetic changes in the rice (Oryza sativa L.) genome are independent of each other

Abstract

An array of studies have reported that the spaceflight environment is mutagenic and may induce phenotypic and genetic changes in diverse organisms. We reported recently that in at least some plant species (e.g., rice) the spaceflight environment can be particularly potent in generating heritable epigenetic changes in the form of altered cytosine methylation patterns and activation of transposable elements. To further study the issue of spaceflight-induced genomic instability, and in particular to test whether the incurred genetic and epigenetic changes are connected or independent of each other, we performed the present study. We subjected seeds of the standard laboratory rice (Oryza sativa L.) cultivar Nipponbare to a spaceflight in the spaceship Long March 2 for 18 days. We then investigated the genetic and DNA methylation stabilities of 11 randomly selected plants germinated from the spaceflown seeds by using two kinds of DNA markers, amplified fragment length polymorphism (AFLP) and methylation sensitive amplified polymorphism (MSAP). For AFLP, by using 15 primer combinations, we assessed 460 genomic loci and found that the frequencies of genetic changes across the 11 plants ranged from 0.7% to 6.7% with an average frequency of 3.5%. For MSAP, by using 14 primer combinations, we assessed 467 loci and detected the occurrence of four major types of cytosine methylation alterations at the CCGG sites, namely CG or CNG hypomethylation and CG or CNG hypermethylation. Collectively, the frequencies of the two kinds of hypermethylation, CG (1.95%) and CNG (1.44%), are about two times higher than those of the two kinds of hypomethylation, CG (0.76%) and CNG (0.80%), though different plants showed variable frequencies for each type of alteration. Further analysis suggested that both the genetic and cytosine methylation changes manifested apparent mutational bias towards specific genomic regions, but the two kinds of instabilities are independent of each other based on correlation analysis.

Post-Spaceflight (STS-135) Mouse Splenocytes Demonstrate Altered Activation Properties and Surface Molecule Expression

“…Both hypo- and hypermethylation events can occur, with concurrent dysregulation of gene expression. Genes for DNA methyltransferases were very sensitive to spaceflight conditions [ 60 , 61 ]. Similar effects were identified in microgravity studies in human lymphocytes [ 62 , 63 ], where both DNA methylation genes, as well as histone acetylation genes, were affected.…”

The Stem Cell State in Plant Development and in Response to Stress

“…This activation was correlated with alteration in cytosine methylation pattern of the mPing element (Ngezahayo et al, 2009). Similarly, MITEs and long terminal repeat (LTR) retrotransposons were activated in certain rice cultivars under spaceflight stress conditions; transposition was correlated with cytosine demethylation within the elements (Long et al, 2009; Ou et al, 2010). Introduction of the tobacco Tnt1 retroelement into Arabidopsis plants resulted in Tnt1 silencing mediated by small interfering RNA-induced non-CG methylation of its LTR; silencing was partly reversed by stresses (Pérez-Hormaeche et al, 2008).…”

Influence of zero gravity on germination, growth, development and phenotype variation in Impatiens balsamia

“…(Gu, Shen, 1989), cây Lúa nước (Oryza spp.) (Luo et al, 2006;Cheng et al, 2007;Ou et al, 2010) và Cà chua (Solanum lycopersicum) (Hammond et al, 1998) được ghi nhận là có sự tăng nảy mầm rõ rệt so với đối chứng trên mặt đất. Hơn nữa, các đặc tính về sinh trưởng phát triển như chiều cao cây, sức sống và đặc biệt là hoạt động của peroxidase isozyme và esterase isozyme được phân lập từ các hạt Lúa mì và Lúa mạch cũng cao hơn so với các hạt đối chứng trên mặt đất và các hạt chiếu tia gamma (Canman et al, 1996).…”