Molecular Genetic Mechanism of Amino Acid Metabolism Regulating Wood Formation

In the process of forest growth and development, wood formation, as the core link of secondary growth, has long been regulated by carbon and nitrogen metabolic balance, but the molecular genetic mechanism of amino acid metabolism, one of its central driving factors, is still unclear, which restricts the molecular breeding process of wood quality improvement. To this end, this study takes poplar as a model plant and constructs a three-in-one cross-level research system. First, liquid chromatography-mass spectrometry (LC-MS) is used to dynamically analyze the changes in amino acid metabolic pathways during xylem development. Then, weighted gene co-expression network analysis (WGCNA) is used to identify transcription factor modules that are highly associated with key metabolic pathways. Finally, CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats / CRISPR-associated protein 9) gene editing is used to construct candidate key gene mutants to clarify the action pathways of metabolic regulation. The results show that the vessel density in PtrASN1 and PtrGDH3 mutants decreases to 41.7/mm², the cell wall thickness decreases to 2.30 μm, and there is a high positive correlation between PtrASN1 expression and cell wall thickness (R² = 0.975). Stable isotope tracing experiments find that the enrichment ratio in mutant lignin significantly decreases to 34.32%. The above results systematically reveals the regulatory mechanism of amino acid metabolism in wood structure development, proposes a regulatory pathway with metabolism-transcription synergy as the core, and provides theoretical support and key targets for molecular design of wood traits and directional breeding.