小 RNA 谱分析表明，一个胚珠特异性 microRNA，cja-miR5179，靶向 Camellia japonica 中的一个 B 类 MADS 框基因。

Small RNA profiling reveals that an ovule-specific microRNA, cja-miR5179, targets a B-class MADS-box gene in Camellia japonica.

机构信息

State Key Laboratory of Tree Genetics and Breeding, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, Zhejiang 311400, China.

College of Information Science and Technology, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.

出版信息

Ann Bot. 2023 Nov 30;132(5):1007-1020. doi: 10.1093/aob/mcad155.

DOI:10.1093/aob/mcad155

PMID:37831901

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10808017/

Abstract

BACKGROUND AND AIMS

The functional specialization of microRNA and its target genes is often an important factor in the establishment of spatiotemporal patterns of gene expression that are essential to plant development and growth. In different plant lineages, understanding the functional conservation and divergence of microRNAs remains to be explored.

METHODS

To identify small regulatory RNAs underlying floral patterning, we performed a tissue-specific profiling of small RNAs in various floral organs from single and double flower varieties (flowers characterized by multiple layers of petals) in Camellia japonica. We identified cja-miR5179, which belongs to a deeply conserved microRNA family that is conserved between angiosperms and basal plants but frequently lost in eudicots. We characterized the molecular function of cja-miR5179 and its target - a B-function MADS-box gene - through gene expression analysis and transient expression assays.

KEY RESULTS

We showed that cja-miR5179 is exclusively expressed in ovule tissues at the early stage of floral development. We found that cja-miR5179 targets the coding sequences of a DEFICIENS-like B-class gene (CjDEF) mRNA, which is located in the K motif of the MADS-box domain; and the target sites of miR5179/MADS-box were consistent in Camellia and orchids. Furthermore, through a petal transient-expression assay, we showed that the BASIC PENTACYSTEINE proteins bind to the GA-rich motifs in the cja-miR5179 promoter region and suppresses its expression.

CONCLUSIONS

We propose that the regulation between miR5179 and a B-class MADS-box gene in C. japonica has a deep evolutionary origin before the separation of monocots and dicots. During floral development of C. japonica, cja-miR5179 is specifically expressed in the ovule, which may be required for the inhibition of CjDEF function. This work highlights the evolutionary conservation as well as functional divergence of small RNAs in floral development.

摘要

背景与目的

microRNA 及其靶基因的功能特化通常是建立对植物发育和生长至关重要的时空基因表达模式的重要因素。在不同的植物谱系中，microRNA 的功能保守性和分化仍有待探索。

方法

为了鉴定控制花部模式形成的小调控 RNA，我们对来自山茶（Camellia japonica）单瓣和重瓣品种（具有多层花瓣的花）不同花器官的小 RNA 进行了组织特异性分析。我们鉴定了 cja-miR5179，它属于一个在被子植物和基生植物中保守但在真双子叶植物中经常丢失的microRNA 家族。我们通过基因表达分析和瞬时表达实验对 cja-miR5179 及其靶基因（一个 B 功能 MADS-box 基因）的分子功能进行了表征。

主要结果

我们表明 cja-miR5179 在花发育早期仅在胚珠组织中表达。我们发现 cja-miR5179 靶向位于 MADS-box 结构域 K 基序中的 DEFICIENS 样 B 类基因（CjDEF）mRNA 的编码序列；并且 miR5179/MADS-box 的靶位在山茶和兰花中是一致的。此外，通过花瓣瞬时表达实验，我们表明 BASIC PENTACYSTEINE 蛋白结合到 cja-miR5179 启动子区域的 GA 富集基序中，并抑制其表达。