Effects of IBA on rooting ability of Cinnamomum bodinieri citral type micro-shoots from transcriptomics analysis

Cinnamomum bodinieri is a useful plant that could be improved by increasing its cultivation rate. To explore the optimal concentration of exogenously applied IBA for root formation and development in the C. bodinieri citral type, micro-shoots and the fresh tissues of their bases were subjected to morphological and transcriptome analyses, respectively. When plantedQuery on a rooting medium (1/2 MS) with 1.5 mg/L IBA for 25 days, the rooting rates and root numbers were significantly higher than those obtained with 0, 0.5, 1.0, or 2.0 mg/L IBA treatment. Transcriptome analyses conducted 0 day, 7 days, 11 days, and 14 days after planting in the optimal rooting medium demonstrated that the IBA modified the plant’s carbohydrate metabolism and auxin signaling pathway. The root-specific expressions of TIR1, GH3, and SAUR were up-expressed while AUX/IAA was repressed, which contributed to the formation of lateral root initiation sites and root cell elongation. At the same time, d-glucose synthesis increased and the accumulation of starch decreased as more carbohydrates were used to form and develop roots instead of being used for the rapid cell division required for shoot growth. This study identified the optimal rooting medium for the C. bodinieri citral type and determined the molecular mechanisms involved in the regulation of exogenously applied IBA during root formation and development at the transcriptional level.