• Circular RNA (circRNA) is a kind of new regulatory RNA with diverse biological functions. Numerous circRNAs have been identified in many plant species; however, evolution of plant circRNAs remains largely unknown.
• In this study, we assembled full-length sequences of 6519 rice (Oryza sativa) circRNAs and analyzed their conservation in another 46 plant species based on comparison of sequences and expression patterns.
• We found that, at the genomic level, 8.7% of the 6519 circRNAs were conserved in dicotyledonous plants and 49.1% in Oryza genus. Meanwhile, 57.8% of parental protein-coding genes of the rice circRNAs originated recently after divergence of monocotyledonous plants, implying recent origin of the majority of rice circRNAs, a conclusion further supported by the results based on analysis of 4663 full-length circRNAs in Arabidopsis thaliana. Accordingly, we proposed three models to address the origination of different types of circRNAs.
• Taken together, the results obtained in this study provide new insights for the evolutionary dynamics of plant circRNAs and candidate circRNAs for further functional exploration.

中文翻译：

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植物中环状RNA的最新起源

• 环状RNA（circRNA）是一种具有多种生物学功能的新型调控RNA。已在许多植物物种中鉴定出大量 circRNA；然而，植物circRNA的进化在很大程度上仍然未知。
• 在这项研究中，我们组装了 6519 个水稻 ( Oryza sativa ) circRNA的全长序列，并基于序列和表达模式的比较分析了它们在另外 46 个植物物种中的保守性。
• 我们发现，在基因组水平上，6519 个 circRNA 中的 8.7% 在双子叶植物中是保守的，在稻属中是49.1% 。同时，57.8% 的水稻 circRNA 亲本蛋白编码基因最近起源于单子叶植物分化后，这意味着大多数水稻 circRNA 起源于近期，这一结论进一步得到了对拟南芥4663 个全长 circRNA 分析结果的支持。拟南芥。因此，我们提出了三种模型来解决不同类型 circRNA 的起源。
• 综上所述，本研究获得的结果为植物circRNA和候选circRNA的进化动力学提供了新的见解，以进行进一步的功能探索。