Effect of Applying Indole-3-butyric Acid on the Rooting of Camellia sinensis Cuttings and the mRNA Expression of Auxin Response Factor (CsARFs)

PurposeTo study the effect of indole-3-butyric acid (IBA) on Nanchuan tea (Camellia sinensis) rooting capacity, the physiological changes during the rooting process and the mRNA expression of CsARFs gene.

MethodThe cuttings were treated with the concentrations of IBA (0, 20, 40, 80, 160 and 320 mg/L). The root capacities were assessed at the end of rooting period, the IAA-oxidase (IAAO) activity, peroxidase (POD) activity and polyphenol oxidase (PPO) activity were determined at 30, 60, 90 and 120 days after planting (DAP). The CsARFs gene expression in the roots was detected at 30, 60, 90 and 120 days with the 80 mg/L IBA-treatment.

ResultIBA had a positive effect on the rooting at the mass concentration of 20, 40, 80 and 160 mg/L IBA, which accompanied with increased POD activity and PPO activity, and decreased IAAO activity, but the 320 mg/L IBA caused a significant reduction of rooting compared with the control (P<0.05). Among of the treatments, the cuttings treated with 80 mg/L IBA had the highest number of roots (NR), callus percentage (CP) and rooting percentage (RP), and higher length of the longest root (LLR) and the mean root length (MRL). Additionally, the mRNA expressions of CsARF 2-1, 2-2, 3-1, 3-2, 8, 9 and 11 were up-regulated in the roots treated by 80 mg/L IBA except 120 days, suggesting these genes involved in promoting rooting process.

ConclusionThe optimal IBA mass oncentration was 80 mg/L for cutting of Nanchuan tea (C. sinensis).