Flavonoid biosynthesis facilitates low nitrogen adaptation in Gleditsia sinensis seedlings: Insights from...

Nitrogen (N) deficiency significantly constrains plant growth and the productivity of plantations. To elucidate the adaptation mechanisms of Gleditsia sinensis (G. sinensis) to low-N stress, an integrated analysis encompassing physiology, transcriptomics, and metabolomics was conducted on low-N tolerant (Changshun1, R) and sensitive (Luoting2, S) genotype seedlings. The findings indicated that although low-N stress markedly decreased biomass and N accumulation, R-type seedlings exhibited higher N use efficiency compared to S-type seedlings. Multi-omics analyses revealed that low-N stress specifically activated phenylpropanoid metabolism and flavonoid/flavonol biosynthesis pathways, with the upregulation of key genes (PAL17.1, PAL2, CYP73A, CHS, and FLS, etc.) resulting in increased accumulation of naringenin, luteolin, kaempferol, and quercetin. These metabolic alterations were potentially regulated by MYB and WRKY transcription factors (TFs), indicating a coordinated molecular response to N limitation. The study demonstrated that G. sinensis adapts to low-N stress through the coordinated regulation of flavonoid biosynthesis and N accumulation, offering novel insights into the low-N adaptation mechanisms of woody seedlings and providing a theoretical foundation for breeding N-efficient G. sinensis varieties.