Medina-Calzada Zahara, Jing Runchun, Moxon Simon, Zhu Hong, Xu Ping, Dalmay Tamas
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
Planta. 2025 Jan 7;261(2):27. doi: 10.1007/s00425-024-04596-8.
A microRNA with a non-canonical precursor structure harbours an intron in between its miRNA-5p and miRNA-3p relevant for its biogenesis, is conserved across Solanaceae, and targets the mRNA of low phosphate root. Hundreds of miRNAs have been identified in plants and great advances have been accomplished in the understanding of plant miRNA biogenesis, mechanisms and functions. Still, many miRNAs, particularly those with less conventional features, remain to be discovered. Likewise, additional layers of regulation from miRNA generation to action and turnover are still being revealed. The current study describes a microRNA not previously identified given its unusual intron-split stem-loop structure, that has been previously observed only within the monocot-specific miRNA444 family. It shows its conservation across a branch of Solanales including agriculturally relevant Solanaceae family, where its transcripts had already been predicted in several species within sequence databases. The miRNA is absent in Arabidopsis thaliana but present in Solanum lycopersicum, Nicotiana benthamiana, Petunia axillaris, and Ipomoea nil. It proves that at least two different pri-miRNA variants are produced from this miRNA gene, one spliced and the other one retaining the intron. It demonstrates the dual function of its intron in the miRNA biogenesis. On the one hand, its presence in the pri-miRNA positively influences mature miRNA accumulation, but on the other hand, it needs to be removed from the pri-miRNA for efficient mature miRNA production. Finally, it sets low phosphate root as one of its targets, a protein known to be involved in root growth regulation under phosphate starvation in other plant species.
一种具有非经典前体结构的微小RNA在其与生物合成相关的miRNA - 5p和miRNA - 3p之间含有一个内含子，在茄科植物中保守，并靶向低磷根的mRNA。在植物中已鉴定出数百种微小RNA，并且在理解植物微小RNA的生物合成、机制和功能方面取得了巨大进展。然而，仍有许多微小RNA，特别是那些具有较少传统特征的微小RNA有待发现。同样，从微小RNA的产生到作用和周转的额外调控层面仍在不断揭示中。当前的研究描述了一种因其不寻常的内含子分裂茎环结构而先前未被鉴定的微小RNA，这种结构以前仅在单子叶植物特有的miRNA444家族中观察到。它显示出在茄目一个分支中的保守性，包括与农业相关的茄科家族，在序列数据库中的几个物种中已经预测到了它的转录本存在。该微小RNA在拟南芥中不存在，但存在于番茄、本氏烟草、腋花矮牵牛和牵牛中。研究证明，该微小RNA基因至少产生两种不同的初级微小RNA变体，一种经过剪接，另一种保留内含子。它证明了其内含子在微小RNA生物合成中的双重功能。一方面，它在初级微小RNA中的存在对成熟微小RNA的积累有积极影响，但另一方面，为了高效产生成熟微小RNA，它需要从初级微小RNA中去除。最后，研究确定低磷根是其靶标之一，低磷根是一种已知在其他植物物种中参与磷饥饿条件下根生长调节的蛋白质。
