Abstract
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.
Highlights
Cinnamomum bodinieri is an excellent tree species for the construction of forests
The Gene ontology (GO), KEGG pathway, and relative expression level clustering analyses demonstrate that during the formation and development of roots, differentially expressed genes (DEGs) were enriched in the auxin signaling pathway (Fig. 4b)
Previous studies show that auxin plays a central role in regulating root growth and development by regulating the expressions of TIR1, AUX/Indole-3-acetic acid (IAA), ARF, GH3, and SAUR
Summary
Cinnamomum bodinieri is an excellent tree species for the construction of forests. It has multiple applications in biomedicines, food additives, spices, cosmetics, and antibacterial agents (Liu et al 2019; Wu et al 2019). Artificial planting of C. bodinieri citral type is mainly achieved via stem cutting cultivation and tissue culture; these techniques result in low survival rates and slow growth, which restrict production. The formation of plant roots is accompanied by cell division and expansion. Phytohormones play important roles in the regulation of cell division and expansion. The phytohormone auxin, which is mainly distributed in young and growing tissues and organs, is critical for plant growth and orchestrates many developmental processes (Yoshihisa et al 2012). Indole-3-acetic acid (IAA) is recognized as the key
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