Transcriptomic Analysis Reveals That Exogenous Indole-3-Butyric Acid Affects the Rooting Process During Stem Segment Culturing of Cinnamomum camphora Linalool Type

Abstract

Cinnamomum camphora linalool type (C. camphora linalool type) is an economically important plant that contains abundant linalool. To explore the optimal concentration of exogenously applied indole-3-butyric acid (IBA) for root formation and development, morphological analyses were performed with plants after a 1-min soaking treatment with five different concentrations of IBA. When grown on the medium (laterite with plant ash) for 60 days after treatment with 3000 mg/L IBA, the root ratio and the number of roots were significantly higher than those obtained with 0, 1000, 2000, or 4000 mg/L IBA treatment. After soaking with 3000 mg/L IBA, the stem bases at five key stages of root development (0, 14, 21, 28, and 42 days) were selected for global transcriptome analyses. IBA treatment modified the expression of genes related to the auxin, brassinosteroid, and abscisic acid signalling transduction pathways. The rooting process reduced the accumulation of starch and the synthesis of linalool but promoted the metabolism of D-glucose. Our study identified the optimum concentration of IBA for a short treatment of C. camphora linalool type stem segments to regulate root formation and development at the transcriptional level.