Bai Yongsheng, Wang Xiaoting, Ali Shahid, Liu Yang, Zhou Jiannan, Liu Meiting, Liu Shuai, Tang Yulin
Guangdong Provincial Key Laboratory for Plant Epigenetics, Guangdong Technology Research Center for Marine Algal Bioengineering, Shenzhen Public Service Platform of Collaborative Innovation for Marine Algae Industry, Longhua Institute of Innovative Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.
Shaanxi Academy of Traditional Chinese Medicine, Xi'an, China.
Plant Genome. 2025 Mar;18(1):e70013. doi: 10.1002/tpg2.70013.
MicroRNAs (miRNAs) control gene expression in plant through transcript cleavage and translation inhibition. Recently, 24-nt miRNAs have been shown to direct DNA methylation at target sites, regulating the neighboring gene expression. Our study focused on miR9560, a 24-nt miRNA induced by cadmium (Cd) stress in Brassica rapa ssp. parachinensis (B. parachinensis). Phylogenetic analysis revealed miR9560 predominantly emerged in the Rosanae superorder and was conserved in Brassicaceae, with potential target sites adjacent to transporter family genes HMAs. RNA gel blotting showed that mature miR9560 was only detected in various Brassica crops roots after Cd stress. In B. parachinensis, miR9560's putative target site is upstream of BrpHMA2, an afflux-type Cd transporter. In a transient expression system of B. parachinensis protoplasts, the expression of miR9560 increased the DNA methylation upstream of BrpHMA2, reducing the transcription of BrpHMA2. This regulation was also observed in Arabidopsis wild-type protoplasts but not in the mutants dcl234 and ago4 with impairments in the RNA-dependent DNA methylation (RdDM) pathway. We deduced that miR9560 modulates BrpHMA2 expression via the RdDM pathway, potentially regulating Cd uptake and movement in B. parachinensis. Furthermore, this regulatory mechanism may extend to other Brassica plants. This study enhances our comprehension of 24-nt miRNAs role in regulating Cd accumulation within Brassica plants.
微小RNA（miRNA）通过转录本切割和翻译抑制来控制植物中的基因表达。最近，已证明24个核苷酸的miRNA可指导靶位点的DNA甲基化，从而调节邻近基因的表达。我们的研究聚焦于miR9560，这是一种在镉（Cd）胁迫下于青菜（Brassica rapa ssp. parachinensis）中诱导产生的24个核苷酸的miRNA。系统发育分析表明，miR9560主要出现在蔷薇超目，并在十字花科中保守，其潜在靶位点与转运蛋白家族基因HMA相邻。RNA凝胶印迹显示，成熟的miR9560仅在镉胁迫后的各种芸苔属作物根部中检测到。在青菜中，miR9560的推定靶位点位于外排型镉转运蛋白BrpHMA2的上游。在青菜原生质体的瞬时表达系统中，miR9560的表达增加了BrpHMA2上游的DNA甲基化，降低了BrpHMA2的转录。在拟南芥野生型原生质体中也观察到了这种调控，但在RNA依赖性DNA甲基化（RdDM）途径受损的dcl234和ago4突变体中未观察到。我们推断，miR9560通过RdDM途径调节BrpHMA2的表达，可能调控青菜中镉的吸收和转运。此外，这种调控机制可能扩展到其他芸苔属植物。这项研究增强了我们对24个核苷酸的miRNA在调节芸苔属植物中镉积累作用的理解。
