Integrative Analysis of Transcriptome and Metabolome Reveals Light Quality-Mediated Regulation of Adventitious Shoot Proliferation in Chinese Fir

Chinese fir (Cunninghamia lanceolata) is an important fast-growing tree species for timber production and ecological protection in China. Yet, its tissue culture for seedling propagation is hampered by low proliferation and poor quality. Light quality is vital for seedling proliferation and growth, but the regulatory mechanisms remain poorly understood. In this study, a transcriptome and metabolome were integrated to explore light quality’s effects on adventitious shoot proliferation of tissue-cultured Chinese fir seedlings. The seedlings were grown under red, green, blue, and composite light-emitting diode conditions, with white light as the control. Results showed that blue and blue-dominant composite light enhanced proliferation by promoting auxin and cytokinin and increased biomass. Red light promoted shoot height, leaf area, and carotenoid content due to elevated gibberellin and reduced auxins and cytokinin levels but inhibited proliferation due to hormonal imbalances. Green light increased abscisic acid levels and suppressed growth. Transcriptome and metabolome analyses identified key pathways including plant hormone signal transduction, photosynthesis, and flavonoid and carotenoid biosynthesis. Weighted gene co-expression network analysis (WGCNA) identified four key genes regulated by light quality that further modulated hormone biosynthesis and signaling transduction. This research provided insights for optimizing Chinese fir seedling proliferation and growth, contributing to sustainable plantation management.