High molecular weight RNAs and small interfering RNAs induce systemic posttranscriptional gene silencing in plants
High molecular weight RNAs and small interfering RNAs induce systemic posttranscriptional gene silencing in plants
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DOI：
10.1073/pnas.182204199
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发表时间：
2002-09-03
影响因子：
11.1
通讯作者：
Meins, F
中科院分区：
文献类型：
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作者：
Klahre, U;Crété, P;Meins, F
转基因植物中的转录后基因沉默 (PTGS) 是一种与 IPTGS 相关的 RNA 降解的表观遗传形式，以及真菌和动物中的 RNA 干扰 (RNAi)。有证据表明，转基因位点和RNA病毒可以产生与靶基因转录区域序列相似的双链RNA，然后进行核酸内切切割，产生小干扰RNA (siRNA)，促进同源RNA的降解。转基因植物和秀丽隐杆线虫中的沉默状态可以系统性传播，这意味着存在移动沉默信号。这些信号的化学性质及其在 PTGS 途径中的确切来源尚不清楚。在这里，我们使用阳性标记系统和绿色荧光蛋白表达的实时监测来显示大正义、反义和双链RNA以及双链siRNA以生物弹道方式递送到植物细胞中触发能够局部和全身传播的沉默。系统性沉默的叶子显示靶标RNA水平大大降低并积累了siRNA，证实RNA可以诱导系统性IPTGS。诱导的 siRNA 代表与触发 siRNA 同源区域之外的靶 RNA 部分。我们的结果表明，siRNA 本身或由 siRNA 诱导的中间体可能包含沉默信号，并且这些信号诱导 siRNA 的自我扩增产生。
Posttranscriptional gene silencing (PTGS) in transgenic plants is an epigenetic form of RNA degradation related to IPTGS, and RNA interference (RNAi) in fungi and animals. Evidence suggests that transgene loci and RNA viruses can generate double-stranded RNAs similar in sequence to the transcribed region of target genes, which then undergo endonucleolytic cleavage to generate small interfering RNAs (siRNA) that promote degradation of cognate RNAs. The silent state in transgenic plants and in Caenorhabditis elegans can spread systemically, implying that mobile silencing signals exist. Neither the chemical nature of these signals nor their exact source in the PTGS pathway is known. Here, we use a positive marker system and real-time monitoring of green fluorescent protein expression to show that large sense, antisense, and double-stranded RNAs as well as double-stranded siRNAs delivered biolistically into plant cells trigger silencing capable of spreading locally and systemically. Systemically silenced leaves show greatly reduced levels of target RNA and accumulate siRNAs, confirming that RNA can induce systemic IPTGS. The induced siRNAs represent parts of the target RNA that are outside of the region of homology with the triggering siRNA. Our results imply that siRNAs themselves or intermediates induced by siRNAs could comprise silencing signals and that these signals induce self-amplifying production of siRNAs.