ABSTRACT
Objective: To obtain the functional genes in Arctium lappa and analyze the key enzyme genes involved in biosynthesis pathway of lignin. Methods: The transcriptome dataset of roots of A. lappa was obtained by using the BGISEQ-500 sequencing platform. Unigenes were de novo assembled and annotated according to the existing nucleic acids and protein databases. The key enzyme genes involved in lignin biosynthesis pathway were analyzed and the three-dimensional model of phenylalanine ammonialyase (AlPAL) was generated by the SWISS-MODEL and PyMol. Results: A total of 54 215 Unigenes were obtained by de novo assembly, and 42 003 Unigenes were annotated in at least one public database. A total of 1 668 Unigenes were identified to be plant transcription factors (TFs), which belong to 54 TF families, and 423 Unigenes were found to be involved in the biosynthesis pathway of lignin. Structure model indicated that AlPAL was a homotypic tetramer, and each monomer was consisted of three domains, including 4-methyl-imidazole-5-ketone (MIO) domain, core domain and shield domain. The MIO domain contained three conserved amino acids (ASG), which formed the catalytic activity center of the enzyme. Conclusion: This study was the first de novo transcriptome assembly of A. lappa, which will lay the foundation for the identification of functional genes, secondary metabolic pathway and the study of regulation mechanism of biosynthesis pathway of lignin in A. lappa in the future.