Comparative Metabolomic Analysis of Benzyl Adenine and Meta-Topolin Riboside Treatments in "Tainung No. 1" Passion...

Meta-topolin riboside (mTR) has shown superior effects over benzyladenine (BA) in promoting root and shoot development in passion fruit tissue culture, yet its underlying mechanisms remain unclear. Understanding the metabolic differences between mTR and BA treatments can inform optimized propagation strategies for high-quality planting material in this economically important crop.

Nodal buds of Passiflora edulis "Tainung No. 1" were cultured on BA- or mTR-supplemented medium, then analyzed using ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) in SWATH acquisition mode. Metabolite features were extracted, statistically filtered (VIP > 1, FC > 1.5 or < 0.667, p < 0.05), identified via multiple databases, and subjected to enrichment and pathway analysis.

SWATH-MS detected 2823 ions in positive and 1637 in negative mode, with 21 significant metabolites identified in each mode. mTR treatment upregulated metabolites linked to root development (e.g., 5,10-methylenetetrahydrofolate, daidzin, and hesperidin) and stem elongation (amygdalin), while BA treatment had higher levels of kinetin, gibberellin A4, and lignans. Pathway analysis highlighted folate metabolism as significantly enriched in mTR samples.

mTR treatment altered phytohormone, flavonoid and phenolic profiles in ways that likely promote rooting, shoot elongation and oxidative stress resilience, explaining its superior growth performance over BA. These insights can guide refined cytokinin use in micropropagation and broader applications in horticultural biotechnology.