Karyobiology Group, Department of Cell Biology, John Innes Centre, NR4 7UH, Norwich, UK.
Theor Appl Genet. 1995 Aug;91(3):529-33. doi: 10.1007/BF00222984.
Ribosomal RNA genes originating from one parent are often suppressed in interspecific hybrids. We show that treatments during germination with the cytosine analogue 5-azacytidine stably reactivate the expression of the suppressed rRNA genes of rye origin in the wheat x rye amphiploid, triticale, by preventing methylation of sites in the rye rDNA. When 5-azacytidine is applied to embryos of triticale and wheat x rye F1 hybrids nine, or more, days after fertilization, rye rRNA gene expression is stably reactivated in the resulting seedling. Earlier treatments have no effect on rye rRNA gene expression, indicating that undermethylation of DNA early in embryo development is reversible. After 9 days, the methylation status of rRNA genes in maintained throughout development. Since the change in expression follows a methylation change at particular restriction-enzyme sites, the data establish a clear correlation between gene activity and methylation in plants.
核糖体 RNA 基因源自一方亲本时，常在种间杂种中受到抑制。我们发现，用胞嘧啶类似物 5-氮杂胞苷处理发芽过程，可通过防止在黑麦 rDNA 中抑制位点的甲基化，稳定地重新激活小麦黑麦异源八倍体小黑麦中黑麦来源的被抑制的 rRNA 基因的表达。当 5-氮杂胞苷施加于受精后 9 天或 9 天以上的小黑麦和小麦黑麦 F1 杂种胚上时，在得到的幼苗中，黑麦 rRNA 基因的表达稳定地重新激活。更早的处理对黑麦 rRNA 基因的表达没有影响，这表明胚胎发育早期 DNA 的低甲基化是可逆的。9 天后，rRNA 基因的甲基化状态在整个发育过程中得以维持。由于表达的变化遵循特定限制酶位点的甲基化变化，这些数据在植物中确立了基因活性与甲基化之间的明确相关性。
