Abstract:

This study aims to deeply analyze that blue light promotes the expansion and development of tuberous roots of Tetrastigma hemsleyanum by regulating endogenous hormone levels and their signaling pathways. Using the MetWare LC-MS/MS platform, we quantified the changes in the contents of eight major plant hormones, including auxin (IAA), cytokinin (CK), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), gibberellin (GA), ethylene (ETH), and strigolactone (SL), along with their intermediates in T. hemsleyanum tubers before and after blue light treatment. Combined with transcriptome sequencing to analyze differentially expressed genes, we correlated hormonal changes with the differential expression of key genes in their signaling pathways and validated target genes using qPCR, thereby investigating the effects of blue light on tuber development from the perspective of transcriptional regulation and hormonal metabolic synergy. Hormone metabolomics revealed that while IAA levels showed no significant change, the expression of its signaling-related genes was markedly downregulated, indicating that IAA contributes minimally to tuber expansion under blue light. The significant accumulation of zeatin-O-glucoside following blue light treatment may indirectly promote tuber development through sucrose metabolism and starch storage. Furthermore, the decrease in GA20 content and stable expression of GID genes led to the attenuation of gibberellin signaling, potentially exerting a positive regulatory effect on tuber swelling. Additionally, blue light significantly upregulated JA levels while suppressing the expression of ThJAZL2663, a negative regulator of JA signal transduction, suggesting that blue light directly enhances JA physiological activity to promote tuber development. Low-intensity blue light irradiation increases JA content and inhibits the expression of ThJAZL2663 gene, thereby amplifying JA physiological activity and directly promoting development. Moreover, blue light exerts a synergistic effect through differential regulation of the hormonal network, including weakening the gibberellin (GA20-GID) signaling pathway and inducing cytokinin glycosylation metabolism, to facilitate tuber expansion in T. hemsleyanum. This study not only elucidates the impact of blue light-mediated hormonal metabolic changes on tuber development but also provides critical theoretical support for optimizing blue light-regulated supplemental cultivation techniques in T. hemsleyanum.

Key words: phytohormone metabolome, transcriptome, low-intensity blue light, Tetrastigma hemsleyanum, development of tuberous root, correlation and comparative analysis