Cistanche deserticola Transcriptome or Gene expression

In this study, we performed deep transcriptome sequencing in fleshy stem of C. deserticola, and about 80 million reads were generated using Illumina pair-end sequencing on HiSeq2000 platform. Using trinity assembler, we obtained 95,787 transcript sequences with transcript lengths ranging from 200bp to 15,698bp, having an average length of 950 bases and the N50 length of 1,519 bases. 63,957 transcripts were identified actively expressed with FPKM = 0.5, in which 30,098 transcripts were annotated with gene descriptions or gene ontology terms by sequence similarity analyses against several public databases (Uniprot, NR and Nt at NCBI, and KEGG). Furthermore, we identified key enzyme genes involved in biosynthesis of lignin and phenylethanoid glycosides (PhGs) which are known to be the primary active ingredients. Four phenylalanine ammonia-lyase (PAL) genes, the first key enzyme in lignin and PhG biosynthesis, were identified based on sequences comparison and phylogenetic analysis. Two biosynthesis pathways of PhGs were also proposed for the first time.

本研究以荒漠肉苁蓉（Cistanche deserticola, C. deserticola）的肉质茎为材料开展深度转录组测序，采用Illumina HiSeq2000平台进行双端测序，共获得约8000万条测序读段（reads）。利用Trinity转录组组装软件进行拼接，共得到95787条转录本序列，转录本长度分布于200bp至15698bp之间，平均长度为950bp，N50长度为1519bp。以FPKM值≥0.5作为活跃表达的筛选标准，共鉴定出63957条活跃表达的转录本；其中30098条转录本通过与多个公共数据库（Uniprot、NCBI的NR、Nt以及KEGG）进行序列相似性比对分析，获得了基因功能描述注释或基因本体（Gene Ontology, GO）术语注释。此外，本研究还鉴定出参与木质素与苯乙醇苷（phenylethanoid glycosides, PhGs）生物合成的关键酶基因，而苯乙醇苷是该物种已知的主要活性成分。基于序列比对与系统发育分析，共鉴定出4个苯丙氨酸解氨酶（phenylalanine ammonia-lyase, PAL）的编码基因——该酶是木质素与苯乙醇苷生物合成途径中的首个关键酶。本研究还首次提出了苯乙醇苷的两条生物合成途径。