Flavell R B, O'Dell M, Metzlaff M
John Innes Centre, Colney, Norwich, Norfolk, UK.
Novartis Found Symp. 1998;214:144-54; discussion 154-67. doi: 10.1002/9780470515501.ch9.
Epigenetic variation affecting pigment pattern formation in petunia flowers due to the insertion of transgenes encoding chalcone synthase is described. The loss of pigment formation in petals or parts of petals is due to the post-transcriptional degradation of chalcone synthase RNA, from both the endogenous petunia chalcone synthase genes and from the chalcone synthase transgenes. The RNA cleavage pathway and its control are described. Different epigenetic states of RNA breakdown are correlated with specific cytosine methylation changes in the coding sequences of the genes. The probability, extent and developmental location of chalcone synthase RNA breakdown are related to the number and organization of transgenes in the genome but epigenetic switches that affect RNA turnover probably occur in meristems and between sexual generations. Hypotheses to explain how the transgenes influence the levels of chalcone synthase RNA breakdown and how different epigenetic states are created are discussed.
本文描述了由于插入编码查尔酮合酶的转基因而导致矮牵牛花花色素模式形成的表观遗传变异。花瓣或花瓣部分色素形成的丧失是由于查尔酮合酶RNA的转录后降解，这既源于矮牵牛内源性查尔酮合酶基因，也源于查尔酮合酶转基因。文中描述了RNA切割途径及其调控。RNA降解的不同表观遗传状态与基因编码序列中特定的胞嘧啶甲基化变化相关。查尔酮合酶RNA降解的概率、程度和发育位置与基因组中转基因的数量和组织有关，但影响RNA周转的表观遗传开关可能发生在分生组织中以及有性世代之间。文中讨论了解释转基因如何影响查尔酮合酶RNA降解水平以及如何产生不同表观遗传状态的假说。
