基于全长转录组测序的掌叶大黄NAC基因家族鉴定分析

Identification and Analysis of NAC Gene Family in Rheum palmatum L.Based on Full-length Transcriptome Sequencing

NAC是植物特有的转录因子家族,本研究基于全长转录组测序分析,系统筛选掌叶大黄(Rheum palmatum)NAC家族,进行编码蛋白理化性质、结构域及系统进化等生物信息分析,利用RNA-seq进行基因组织表达和茉莉酸甲酯(methyl jasmonate, MeJA)处理的表达分析,并用RT-qPCR进行候选基因表达模式验证。结果表明,掌叶大黄NAC基因家族包含32个成员,编码蛋白主要为热稳定性好的亲水性蛋白,大多定位于叶绿体或细胞核,二级结构中α-螺旋与无规则卷曲所占比例大,多数蛋白都含有NAC特有的5个亚结构域。掌叶大黄RpNACs与拟南芥(Arabidopsis thaliana)AtNAC家族成员的系统进化树一致,被分为11个亚家族,NAC2亚家族中成员数量最高。RNA-seq分析揭示RpNACs基因在掌叶大黄叶、根和根茎中差异表达,其中,11个基因在根茎中显著上调、 12个在根中显著上调;MeJA处理12 h后,RpNAC18、RpNAC20、RpNAC23、RpNAC25、RpNAC27、RpNAC30等6个基因显著上调。RT-qPCR检测显示,其中4个候选基因RpNAC20、RpNAC23、RpNAC25、RpNAC27均受MeJA处理诱导,与转录组数据基本一致。本文系统分析掌叶大黄NAC基因家族,为后续深入进行基因功能验证及其在药材品质形成中的作用机制研究提供科学依据。

NAC transcription factor,a family of plant-specific transcription factor.In this study,based on full-length transcriptome se-quencing analysis,the NAC gene family of Rheum palmatum was systematically screened,and biological information such as physical and chemical properties,domain and phylogenetic evolution of encoded proteins were analyzed.RNA-seq was used for gene expression in different tissues and in response to methyl jasmonate(MeJA)treatment,and the expression pattern of candidate genes was verified by RT-qPCR.The results showed that R.palmatum NAC gene family consisted of 32 members,and the encoded proteins were mainly hydrophilie with good thermal stability,most of which were located in chloroplast or nucleus,αhelix and random coil accounted for a large proportion in the secondary structure,and most of the proteins contained five specific subdomain of NAC.RpNACs in R.palmatum were consistent with the phylogenetic tree of AtNAC family members in Arabidopsis thaliana and were divided into 1l subfamilies,with the highest number of members in NAC2 subfamily.RNA-seq revealed that RpNACs genes were differentially expressed in the leaves,roots and rhizomes of R.palmatum,among which Il genes were significantly up-regulated in rhizomes and 12 in roots.Six genes,including RpNACI18,RpNAC20,RpNAC23,RpNAC25,RpNAC27,RpNAC30,were significantly up-regulated after 12 h post MeJA treatment.Four candidate genes RpNAC20,RpNAC23,RpNAC25,RpNAC27 were validated by RT-qPCR,showing induction by MeJA treatment that were basically consistent with transcriptome data.Herein,the NAC gene family of R.palmatum was systematically analyzed to provide scientific basis for further gene function verification and the mechanism of action in the quality formation of medicinal materials.