Application of Trehalose Enhances Drought Resistance in Sugarcane Seedlings and Promotes Plant Growth

This study aims to investigate whether application of trehalose could mitigate the adverse effects of drought stress by enhancing the defense response in sugarcane (Saccharum spp. hybrid), and to provide a theoretical basis for stable high yield of sugarcane under drought conditions.

The present investigation was conducted to assess ameliorative effects of adding trehalose on the growth, malondialdehyde (MDA) content, and antioxidant responses of two sugarcane cultivars ROC22 and YZ05-51 under the treatment of 30% PEG6000 and 12% PEG6000. In the preliminary experiment, four treatment concentrations of trehalose were set at 0, 10, 100 and 200 mg·L^-1. The dry weight, fresh weight and adventitious roots of tissue-cultured sugarcane seedlings were measured at 9 d after treatment to clarify the optimal concentration of trehalose in promoting sugarcane growth under drought stress. Then, the MDA content and the activity of antioxidant enzyme peroxidase (POD) and superoxide dismutase (SOD) were determined under control, drought stress and drought stress combined with optimal trehalose treatment. Finally, the expression level of drought-resistance genes ScTPS1, ScSnRK2.3, ScSnRK2.4 and ScDREB2b-1 was quantified by qRT-PCR at 0, 12, 24 and 48 h in YZ05-51 after exposed to 30% PEG6000 and 30% PEG6000 adding with optimal trehalose concentration, respectively.

Application of trehalose could alleviate the drought-induced decrease of fresh weight and dry weight of two sugarcane cultivars, and the growth recovery of plantlet was better in 100 mg·L^-1 trehalose group than that in 10 and 200 mg·L^-1 trehalose groups. Under 30% PEG6000 stress, the MDA content was notably increased, and a considerable improvement was recorded in the activity of the antioxidant enzymes POD and SOD. Adding trehalose significantly reduced the content of drought-induced MDA, and enhanced the activity of POD and SOD, respectively. However, external trehalose had little effect on the MDA content and antioxidant enzyme activity of tissue-cultured sugarcane seedlings under 12% PEG6000 stress. Compared with drought controls, the expression of drought-resistance genes ScTPS1, ScSnRK2.3, ScSnRK2.4 and ScDREB2b-1 was up-regulated in the trehalose-treated plantlet.

Application of trehalose can alleviate the negative impact of drought on the growth of sugarcane seedlings, and promote adventitious root growth. External addition of trehalose may reduce the oxidative toxicity caused by drought stress by increasing the activity of antioxidant enzymes POD and SOD. Meanwhile, application of trehalose induces the expression of drought-resistance genes ScTPS1, ScSnRK2.3, ScSnRK2.4, and ScDREB2b-1, indicating that applying trehalose can improve the drought resistance of sugarcane. The results will provide a reference for developing drought resistance strategies in sugarcane breeding and productive practice.