Exogenous Auxin Analogues Promoted Root Growth by Trigging Antioxidant Enzyme System in Dracaena Sanderiana
摘要
Dracaena sanderiana cuttings is extremely popular as its high ornamental value and beautiful symbolism. This study aimed to assess effects of three exogenous auxin analogues, namely IBA (indole-3-butyric acid), 2,4-D (2,4-dichloro-phenoxyacetic acid) and NAA (naphthalene acetic acid), on root growth and antioxidant enzyme activities in Dracaena sanderiana cuttings. The results showed that: IBA performed the most positive effect on root growth and development in Dracaena sanderiana, especially with 1.5 g/L IBA application. Specifically, the root number and root length were improved by 3.5 and 3.1 times with 1.5 g/L IBA application relative to CK. Unexpectedly, the chlorophyll contents decreased after the application of these three auxin analogues, probably due to its biomass allocation strategy between aboveground part and underground part in plant. Moreover, compared to CK, the root activity increased by 28.1% and 30.0% at 1.5 g/L IBA and 10 mg/L NAA, respectively. And root cell membrane permeability was maintained at about 80.0% under three auxin analogues. Dramatically, IBA was also more effective than the other two auxin analogues for MDA (malondialdehyde) and H2O2 (hydrogen peroxide) contents (specifically, decrease of 33.8%, 33.1% at 1.5 g/L IBA relative to CK). Besides, IBA showed more stable effect on antioxidant enzyme activities compared with 2,4-D and NAA. In particular, the activities of SOD (superoxide dismutase), POD (peroxidase), CAT (catalase) in 1.5 g/L IBA were increased by 2.4%, 6.3%, 97.7% compared with CK, separately. Therefore, we conclude that IBA can improve root growth by enhancing antioxidant enzyme activities and mitigating lipid peroxidation in Dracaena sanderiana. These results were expected to provide a theoretical basis for understanding the effects of different exogenous auxin analogues on root growth and development for Dracaena sanderiana cuttings.