School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia.
Plant Cell Physiol. 2018 Nov 1;59(11):2169-2187. doi: 10.1093/pcp/pcy167.
Small regulatory RNAs guide gene silencing at the DNA or RNA level through repression of complementary sequences. The two main forms of small RNAs are microRNA (miRNA) and small interfering RNA (siRNAs), which are generated from the processing of different forms of double-stranded RNA (dsRNA) precursors. These two forms of small regulatory RNAs function in distinct but overlapping gene silencing pathways in plants. Gene silencing pathways in eukaryotes evolved from an ancient prokaryotic mechanism involved in genome defense against invasive genetic elements, but has since diversified to also play a crucial role in regulation of endogenous gene expression. Here, we review the biogenesis of the different forms of small RNAs in plants, including miRNAs, phased, secondary siRNAs (phasiRNAs) and heterochromatic siRNAs (hetsiRNAs), with a focus on their functions in genome defense, transcriptional and post-transcriptional gene silencing, RNA-directed DNA methylation, trans-chromosomal methylation and paramutation. We also discuss the important role that gene duplication has played in the functional diversification of gene silencing pathways in plants, and we highlight recently discovered components of gene silencing pathways in plants.
小调控 RNA 通过抑制互补序列在 DNA 或 RNA 水平上指导基因沉默。两种主要的小 RNA 形式是 microRNA (miRNA) 和 small interfering RNA (siRNA)，它们是从不同形式双链 RNA (dsRNA) 前体的加工中产生的。这两种形式的小调控 RNA 在植物中通过不同但重叠的基因沉默途径发挥作用。真核生物中的基因沉默途径是从一种古老的原核机制进化而来的，该机制涉及基因组防御入侵遗传元件，但后来多样化，也在调节内源性基因表达中发挥关键作用。在这里，我们回顾了植物中小 RNA（包括 miRNA、相分离的、次级 siRNA（phasiRNA）和异染色质 siRNA（hetsiRNA））的不同形式的生物发生，重点讨论它们在基因组防御、转录和转录后基因沉默、RNA 指导的 DNA 甲基化、跨染色体甲基化和位置突变中的功能。我们还讨论了基因复制在植物基因沉默途径功能多样化中所起的重要作用，并强调了植物基因沉默途径中最近发现的成分。
