Analysis of key genes and their expression characteristics related to terpenoid biosynthesis in Tussilago farfara based on transcriptome sequencing

Run-Li HE

ABSTRACT

Objective:

To screen candidate genes involved in the terpenoid biosynthetic pathway of Tussilago farfara.

Methods:

The transcriptome of buds and leaves of wild T. farfara were respectively sequenced using the Illumina HiSeq 2500 high-throughput sequencing platform. The clean reads were de novo assembled by Trinity software, and the assembled sequences then followed by a series of bioinformatics analysis such as gene function annotation and differential expression gene. According to sequence annotation and differentially expressed genes analysis, the key enzyme genes related to the terpenoid biosynthesis were identified.

Results:

After high through-put sequencing, a total of 39 912 371 clean reads were obtained (SRA accession SRR9113366, SRR9113367). The clean reads were then assembled into 91 118 unigenes. A total of 55 830 unigenes were annotated by a similarity search against NR, Swiss-Port, GO, COG, KEGG five public databases. Base on KEGG annotation and differentially expressed genes, totally 129 catalytic enzyme genes referring to the terpenoid biosynthesis were identified, including 91 terpenoid backbone biosynthesis genes, 32 terpene synthases, and 6 cytochrome P450 (CYP450) genes. Among them, 25 genes were differentially expressed. The expression of four enzyme genes in MVA pathway in leaves were higher than that in buds, while the five enzyme genes in MEP pathway were lower in leaves than that in buds. In addition, 10 genes were highly expressed in leaves, and nine genes were highly expressed in buds. According to the high expression of differentially expressed HMGR, TPS, AS, CYP450 genes in buds, it was speculated that these genes may be related to the high content of terpenoids in flower buds.

Conclusion:

This work obtained candidate key enzyme genes that may be involved in the biosynthesis of terpenoid by transcriptome sequencing. The results laid a foundation for further elucidating the molecular mechanism of terpenoid biosynthetic pathway in T. farfara.