Xia Rui, Xu Jing, Meyers Blake C
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, Guangdong 510642, China
College of Horticulture, South China Agricultural University, Guangzhou, Guangdong 510642, China.
Plant Cell. 2017 Jun;29(6):1232-1247. doi: 10.1105/tpc.17.00185. Epub 2017 Apr 24.
In plants, miR390 directs the production of tasiRNAs from () transcripts to regulate () genes, critical for auxin signaling; these tasiRNAs are known as tasiARFs. To understand the evolution of this miR390-- pathway, we characterized homologs of these three genes from thousands of plant species, from bryophytes to angiosperms. We found the lower-stem region of genes, critical for accurate DICER-LIKE1 processing, is conserved in sequence in seed plants. We propose a model for the transition of functional tasiRNA sequences in genes occurred at the emergence of vascular plants, in which the two miR390 target sites of genes showed distinct pairing patterns. Based on the cleavability of miR390 target sites and the distance between target site and tasiARF, we inferred a potential bidirectional processing mechanism exists for some genes. We also demonstrated a tight mutual selection between tasiARF and its target genes and that ARGONAUTE7, the partner of miR390, was specified later than other factors in the pathway. All these data illuminate the evolutionary path of the miR390-- pathway in land plants and demonstrate the significant variation that occurs in this functionally important and archetypal regulatory circuit.
在植物中，miR390指导从（）转录本产生tasiRNAs，以调控（）基因，这些基因对生长素信号传导至关重要；这些tasiRNAs被称为tasiARFs。为了解这条miR390 - 通路的进化过程，我们对从苔藓植物到被子植物的数千种植物物种中的这三个基因的同源物进行了特征分析。我们发现，对于精确的DICER-LIKE1加工至关重要的基因的下游茎区在种子植物中序列保守。我们提出了一个关于功能性tasiRNA序列在基因中转变的模型，该转变发生在维管植物出现时，其中基因的两个miR390靶位点呈现出不同的配对模式。基于miR390靶位点的可切割性以及靶位点与tasiARF之间的距离，我们推断某些基因存在潜在的双向加工机制。我们还证明了tasiARF与其靶基因之间存在紧密的相互选择，并且miR390的伙伴AGO7在该通路中比其他因子确定得更晚。所有这些数据揭示了陆地植物中miR390 - 通路的进化路径，并证明了在这个功能重要且典型的调控回路中发生的显著变异。
