兰花花色苷合成相关R2R3-MYB基因的全基因组鉴定与分析

Genome-wide identification and analysis of anthocyanin synthesis-related R2R3-MYB genes in Cymbidium goeringii

摘要

The MYB gene family plays a vital regulatory role in plant metabolism, stress response, and floral color. The R2R3-MYB gene family of C. goeringii was identified, and its expression was analyzed using bioinformatics in this article. The R2R3-MYB genes of Arabidopsis thaliana were used as a reference to determine 104 CgMYB genes and categorize them into 22 subfamilies. Exon/intron organizations and conserved motif analysis revealed that the majority of CgMYB genes were highly conserved, and chromosome localization and collinearity analysis provided evidence of tandem duplication and segmental duplication events, indicating the phenomenon of gene family expansion and contraction. The function of CgMYB genes was analyzed by cis-acting element and gene ontology (GO) enrichment. In addition, we selected CgMYB91 and CgMYB32 for RT–qPCR, suggesting that CgMYB91 and CgMYB32 are associated with anthocyanin formation. In short, this study provides a comprehensive and specific function of the R2R3-MYB transcription factors (TFs) in orchids.

MYB基因家族在植物的新陈代谢、胁迫响应和花色调控中发挥重要的调控作用。本研究鉴定了C. goeringii（春兰）的R2R3-MYB基因家族，并利用生物信息学方法分析其表达模式。以拟南芥（Arabidopsis thaliana）的R2R3-MYB基因为参考，共鉴定出104个CgMYB基因，并将其划分为22个亚家族。外显子/内含子结构及保守基序分析表明，大多数CgMYB基因具有较高的保守性；染色体定位及共线性分析则揭示了串联重复和片段重复事件的存在，表明该基因家族经历了扩张与收缩的过程。通过顺式作用元件分析和基因本体（GO）富集分析探讨了CgMYB基因的功能。此外，我们选择CgMYB91和CgMYB32进行RT-qPCR验证，结果表明这两个基因与花青素的形成相关。总的来说，本研究为**兰科植物R2R3-MYB转录因子（TFs）**的功能提供了全面的解析。

Introduction  介绍

Transcription factors (TFs) are mostly engaged in regulating plant growth and metabolism. The avian myeloblastosis viral oncogene homolog (v-MYB, MYB) was first identified in vertebrates and widely found in eukaryotes (Smita et al., 2015; Zhao et al., 2020a). In plants, the MYB gene was first identified in maize (Zea mays) and named ZmMYBC1 in Paz-Ares et al. (1987). Subsequently, it was identified and studied in model species such as A. thaliana and Oryza sativa, and the functions of multiple MYB genes were identified. The MYB TF family influences many aspects of plant growth processes. It plays a critical role in regulating various environmental stress responses and secondary metabolism, also controlling the morphology and pattern of the cells (Lloyd et al., 2017; Li J. et al., 2019; Li X. et al., 2019; Cao et al., 2020; Chen H. et al., 2020). As a superfamily, MYB TFs can be categorized into four subgroups based on their one to four conserved MYB domains (R domains), called 1R-MYB factors (MYB-related), R2R3-MYB factors, 3R-MYB factors, and 4R-MYB factors. The R domain consists of approximately 52 amino acids that form three alpha-helices, containing one tryptophan for every 18 amino acids. The common feature of MYB TFs is that they all have DNA binding domains at the N-terminus of the protein.

转录因子（TFs）主要参与调控植物的生长和新陈代谢。禽类髓母细胞瘤病毒癌基因同源物（v-MYB, MYB）最早在脊椎动物中被发现，并广泛存在于真核生物中（Smita et al., 2015; Zhao et al., 2020a）。在植物中，MYB基因最早在玉米（Zea mays）中被鉴定，并被命名为ZmMYBC1（Paz-Ares et al., 1987）。随后，该基因在**拟南芥（Arabidopsis thaliana）和水稻（Oryza sativa）**等模式物种中被鉴定和研究，并解析了多个MYB基因的功能。

MYB转录因子家族在植物的多个生长过程中发挥重要作用，不仅参与环境胁迫响应和次生代谢调控，还控制细胞的形态和模式（Lloyd et al., 2017; Li J. et al., 2019; Li X. et al., 2019; Cao et al., 2020; Chen H. et al., 2020）。作为一个超家族，MYB TFs可根据其一个至四个保守的MYB结构域（R结构域）分为四个亚类，即1R-MYB因子（MYB-related）、R2R3-MYB因子、3R-MYB因子和4R-MYB因子。

R结构域由约52个氨基酸组成，形成三个α螺旋，且每18个氨基酸中通常包含一个色氨酸（tryptophan）。MYB转录因子的共同特征是其蛋白N端（N-terminus）具有DNA结合结构域。

One of the most prominent groups of MYB TFs is the R2R3-MYB family in plants (Hou et al., 2018a). R2R3-MYB involves conserved DNA-