Release from post-transcriptional gene silencing by cell proliferation in transgenic tobacco plants: possible mechanism for noninheritance of the silencing.
Release from post-transcriptional gene silencing by cell proliferation in transgenic tobacco plants: possible mechanism for noninheritance of the silencing.
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发表时间：
2002
期刊：
影响因子：
3.3
通讯作者：
I. Mitsuhara;Naomi Shirasawa-Seo;T. Iwai;Shigeo Nakamura;R. Honkura;Y. Ohashi
中科院分区：
文献类型：
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作者：
I. Mitsuhara;Naomi Shirasawa-Seo;T. Iwai;Shigeo Nakamura;R. Honkura;Y. Ohashi
过量产生荧光素酶（Luc）的转基因烟草植物经常表现出luc的转录后基因沉默（PTGS）。在五代中观察到沉默，发现沉默不是遗传的，而是由下一代以一定的频率获得的。Luc成像分析沉默的植物显示Luc活性仅在增殖组织，如芽分生组织和发育中的花。luc基因表达已从生殖细胞发育前的沉默中恢复，排除了在减数分裂时从PTGS中恢复的可能性。从较老组织转移的系统性沉默信号可能诱导细胞增殖已经完成的较年轻组织的基因沉默。只有种子保持Luc活性，可能是因为从亲本胎盘的可能分区的沉默信号的隔离。新诱导的愈伤组织从沉默植物的叶片中恢复，并表现出与非沉默叶片相似的强Luc活性，进一步表明沉默不能在增殖细胞中维持。因此，增殖细胞中PTGS的释放是沉默非遗传的一种可能机制。
Transgenic tobacco plants that overproduce luciferase (Luc) frequently exhibit post-transcriptional gene silencing (PTGS) of luc. The silencing was observed over five generations and found not to be inherited but acquired by the next generation at a certain frequency. Luc imaging analysis of silenced plants revealed Luc activity only in proliferating tissues such as shoot meristem and developing flower. The luc gene expression has been recovered from silencing before development of germ cells, excluding a possible recovery from the PTGS at meiosis. A systemic silencing signal transferred from older tissue likely induces gene silencing of younger tissues in which cell proliferation has been completed. Only seeds maintained Luc activity, probably because of isolation from the silencing signal by a possible partition from the parent placenta. Calli newly induced from the leaf pieces of silenced plants recovered from the silencing and exhibited strong Luc activity similar to nonsilenced leaves, further indicating that the silencing cannot be maintained in proliferating cells. Thus release from PTGS in proliferating cells is a possible mechanism for noninheritance of silencing.