Integrative analysis of wood biomass and developing xylem transcriptome provide insights into mechanisms of lignin biosynthesis in wood formation of Pinus massoniana.

Lignin is an important renewable energy source as an excellent new battery fuel and ideal substitutes for the petrochemical industry. However, the molecular mechanism underlying lignin biosynthesis in wood formation of P. massoniana remains unexplored. Thus, an integrative analysis of wood biomass and the developing xylem transcriptome was performed to identify genes involved in lignin biosynthesis. A total of 1624 differentially expressed genes (DEGs) were identified, consisting of 797 upregulated and 827 downregulated genes (MaxG vs MinG). Additionally, 122 candidate genes and 17 DEGs were successfully annotated to the lignin biosynthesis pathway. All upregulated MYB and NAC genes were regulators of secondary cell wall formation. Moreover, the qRT-PCR analyses shown that 9 lignin biosynthesis-related genes and 7 transcription factor-encoding genes were upregulated (MaxG vs MinG), which indicated that the downregulation of lignin biosynthesis-related genes might be the possible causes of growth retardation and dwarf phenotype in some P. massoniana individuals. The identification of lignin biosynthesis-related genes can provide valuable genetic basis and resource for further researches on molecular mechanisms of lignin biosynthesis and contribute to the future investigations of bioengineering and synthetic biology to regulate lignin content in wood formation for the pulp and wood utilization industry.