Quantitative Analysis of phytohormone dynamics during the induction phase of adventitious root formation in woody plants with varying rooting capacities

Abstract Adventitious root (AR) formation is a crucial process in vegetative propagation, influenced by endogenous hormonal signaling and species-specific physiological responses. This study investigates the dynamics of key phytohormones—indole-3-acetic acid (IAA), its inactive conjugate IAA-Asp, chlorinated auxin 4-Cl-IAA, jasmonic acid (JA), and its active form JA-Ile—during the induction phase of AR development in three woody plants with differing rooting capacities: Prunus subhirtella ‘Autumnalis’ (easy-to-root), Castanea crenata × Castanea sativa ‘Marsol’ (intermediate), and Castanea sativa ‘Kozjak’ (difficult-to-root). Leafy cuttings were monitored at five time points (0 min, 30 min, 1 h, 4 h, 24 h) after severance for hormone profiling via HPLC-MS/MS. Rooting performance was assessed at the end of the growing season. Results revealed genotype-specific hormonal profiles and temporal regulation patterns. Successful rooting correlated with a transient IAA peak and rapid attenuation of JA and JA-Ile signals. Conversely, high early auxin levels in C. sativa ‘Kozjak’ were accompanied by increased IAA-Asp and poor rooting outcomes. Principal component analysis underscored distinct hormone interactions across genotypes. These findings highlight the importance of hormone timing, concentration, and conjugation in AR formation and provide insights for improving propagation protocols in woody plants.