绣球茜花萼的差异表达基因分析及其颜色调控转录因子的筛选

Analysis of Differentially Expressed Genes in the Calyx of Dunnia sinensis and Screening of Transcription Factors for Color Regulation

摘要:

绣球茜(Dunnia sinensis)是我国广东特有的、国家二级珍稀濒危植物，有明显脉纹的白色变态花萼裂片，具有良好的观赏价值，但目前尚未有其基因组信息。为研究绣球茜花萼发育的分子调控机制，挖掘相关的功能基因，对其萼片、果实、叶片及花瓣进行RNA-seq和差异基因表达分析，以期筛选萼片特异表达基因或信号途径。结果表明，与叶片相比，萼片差异表达的基因有3 972个，主要富集于代谢途径、次生代谢生物合成、光合作用、苯丙类生物合成等途径。与花瓣相比，萼片差异表达的基因有9 680个(上调3 616个，下调6 024个，FC>2)，主要富集于植物激素、苯丙类生物合成、植物与病原互作、次生代谢生物合成等途径。与果实相比，萼片差异表达的基因有4 655个(上调1 827个，下调2 828个，FC>2)，富集的途径和参与调控途径近似于花瓣的转录组。聚类分析表明，参与萼片发育且特异高表达的转录因子主要有3类：ERFs、MYBs和WRKYs，其中MYB家族的DsTMYB3可能参与萼片的颜色调控。组织的高表达基因分析表明，UBI11启动子在各组织中广泛表达，而CSLG2启动子等特异在花萼高表达，这些基因的启动子将作为遗传工具驱动目的基因组成型表达或特异表达于花萼。通过分析绣球茜花萼和其他组织的差异表达基因，获得了可能参与萼片颜色调节的相关转录因子和启动子, 这将为绣球茜的遗传转化和功能研究提供基础。

Abstract:

Dunnia sinensis is a rare and endangered plant unique to Guangdong Province. It has white metaseptic calyx segments with obvious veins and has good ornamental value. However, there is no genomic information about it. In order to understand the molecular regulation of calyx development and explore related functional genes, the expression of RNA-seq and differential genes in sepals, fruits, leaves and petals of D. sinensis were analyzed, to screening the specific expression genes or signaling pathways in sepals. The results showed that there were 3 972 differentially expressed genes in sepals compared with leaves, which were mainly concentrated in metabolic pathways, secondary metabolic biosynthesis, photosynthesis, phenyl-C biosynthesis, etc. Compared with petals, there were 9 680 differentially expressed genes (3 616 up-regulated, 6 024 down-regulated, FC>2) in sepals, which were mainly concentrated in plant hormones, phenyl-C biosynthesis, plant pathogen interaction, secondary metabolic biosynthesis and other pathways. Compared with fruit, there were 4 655 differentially expressed genes (1 827 up-regulated, 2 828 down-regulated, FC>2) in sepals, and the enrichment and regulation pathways of differential gene were similar to those of petal transcriptome. Cluster analysis showed that there were three types of transcription factors involved in the development of sepals with specific high expression: ERFs, MYBs and WRKYs. Among them, DsTMYB3 of the MYB family might be involved in the color regulation of sepals. Analysis of highly expressed genes in tissues showed that UBI11 promoter was widely expressed in all tissues, while CSLG2 promoter were specifically expressed in calyx, and the promoters of these genes would be used as genetic tools to drive the targeted genome forming expression or specific expression in calyx. Therefore, some of differentially expressed genes between calyx and the other tissues of D. sinensis, might be involved in the color regulation of sepals, which would provide a basis for the genetic transformation and functional study of D. sinensis.