Physiological and transcriptomic analysis reveal the regulation of IBA-induced adventitious root formation in three stone fruit rootstock cuttings

Adventitious root (AR) formation is a major limiting factor for the cutting propagation of peach rootstocks, and IBA-induced rooting is a complex biological process orchestrated by the crosstalk between exogenous and endogenous signaling pathways. In this study, three continuous-cropping tolerant peach clonal rootstocks, including ‘GF677’, ‘Cadaman’, and ‘Zhongtao Kangzhen No.1’, were used to explore the physiological and molecular regulatory mechanisms of exogenous IBA on ARs development. The results showed that the optimal IBA concentration varied among rootstocks: 300 mg·L ^− 1 for ‘GF677’ (91% rooting rate), 800 mg·L ^− 1 for ‘Cadaman’ (81% rooting rate), and 500 mg·L ^− 1 for ‘Zhongtao Kangzhen No.1’ with the highest rooting rate of 95%. Exogenous IBA significantly enhanced the activities of POD and IAAO in cuttings. The maximum IAA/CTK ratio was observed at 21 d in ‘GF677’, 28 d in ‘Cadaman’, and 35 d in ‘Zhongtao Kangzhen No.1’. The MDA accumulation dynamics differed distinctly among rootstocks, indicating diverse temporal responses of membrane lipid peroxidation and oxidative stress during rooting. Correlation analysis revealed a significantly negative correlation between TN and TK, while IAA was extremely positively correlated with CTK, and MDA was positively correlated with both hormones. A total of 9,170 DEGs were identified via transcriptome sequencing at the key rooting stages, with ‘Zhongtao Kangzhen No.1’ exhibiting the most prominent transcriptional response. GO and KEGG analyses demonstrated significant enrichment of plant hormone signal transduction pathways, in which the auxin signaling pathway played a dominant role. Numerous hormone-related transcription factor families, including RLK-Pelle_DLSV, MYB, and NAC, were identified. This study systematically clarifies the regulatory mechanism of IBA-induced adventitious rooting in peach rootstocks and provides a theoretical basis for the genetic improvement of peach cutting propagation.