SMRT and Illumina sequencing provide insights into mechanisms of lignin and terpenoids biosynthesis in Pinus massoniana Lamb.

ABSTRACT

Wood and oleoresin are important industrial raw materials with high economic value; however, their molecular formation and biosynthesis mechanisms in different tissues of Pinus massoniana remain unexplored. Therefore, we used single-molecule real-time sequencing technology (SMRT) and Illumina RNA sequencing to establish a transcriptome dataset and explore the expression pattern of genes related to secondary metabolites involved in wood formation and oleoresin biosynthesis in six different P. massoniana tissues. In total, 63.58 Gb of polymerase reads were obtained, including 41,407 isoforms with an average length of 1822 bp. We identified 3939 and 8785 isoforms and 161 and 481 transcription factors with tissue expression specificity and in the reproductive and vegetative organs, respectively. Eighty isoforms were annotated as cellulose synthases and 224 isoforms involved in lignin biosynthesis were enriched. Additionally, we identified 217 isoforms involved in the terpenoid biosynthesis pathway, with needles having the most tissue-specific genes for terpenoid biosynthesis. Some isoforms related to lignin biosynthesis were highly expressed in the xylem, according to the results of transcriptome sequencing and real-time quantitative reverse-transcription polymerase chain reaction. Our research confirmed the advantages of SMRT sequencing and provided valuable information for the transcriptional annotation of P. massoniana, which will be beneficial for producing better raw wood and oleoresin materials.