Trehalose is a nonreducing disaccharide of glucose that functions as a protectant in the stabilization of biological structures and enhances stress tolerance to abiotic stresses in organisms. We report here the expression of a Grifola frondosa trehalose synthase (TSase) gene for improving drought tolerance in sugarcane (Saccharum officinarum L.). The expression of the transgene was under the control of two tandem copies of the CaMV35S promoter and transferred into sugarcane by Agrobacterium tumefaciens EHA105. The transgenic plants accumulated high levels of trehalose, up to 8.805-12.863 mg/g fresh weight, whereas it was present at undetectable level in nontransgenic plants. It has been reported that transgenic plants transformed with Escherichia coli TPS (trehalose-6-phosphatesynthase) and/or TPP (trehalose-6-phosphate phosphatase) are severely stunted and have root morphologic alterations. Interestingly, our transgenic sugarcane plants had no obvious morphological changes and no growth inhibition in the field. Trehalose accumulation in 35S-35S:TSase plants resulted in increased drought tolerance, as shown by the drought and the drought physiological indexes, such as the rate of bound water/free water, plasma membrane permeability, malondialdehyde content, chlorophyll a and b contents, and activity of SOD and POD of the excised leaves. These results suggest that transgenic plants transformed with the TSase gene can accumulate high levels of trehalose and have enhanced tolerance to drought. FH (2006). Expression of the Grifola frondosa trehalose synthase gene and improvement of drought-tolerance in sugarcane (Saccharum officinarum L.). J Integrat Plant Biol 48(4), 453−459.

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Optimum fertilization is one of the challenges to agricultural sustainability. Understanding the physiological and biochemical response of plants to available nutrients is important for optimization of crop management practices. Present study investigated the effects of different levels of N fertilizer (N0 = 0 kg ha−1 [Control], N1 = 140 kg ha−1 [Low], N2 = 280 kg ha−1 [Medium], and N3 = 420 kg ha−1 [High]) on growth, gaseous exchange, antioxidant capacity, and N metabolism in ramie (Boehmeria nivea L.) under greenhouse conditions in a completely randomized design (CRD) with three replications. Nitrogen application improved the plant growth, chlorophyll contents, and antioxidant activity of ramie; the maximum shoot fresh biomass (91 g), shoot dry biomass (13.7 g), number of leaves (46.5), and number of stems (6.4) were recorded at medium N rate. However, the growth was reduced under high N rate. Except for intercellular CO2 concentration, all the other gas exchange parameters were significantly affected by the N levels. Increasing N level improved the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), and enhanced the chlorophyll and soluble protein contents in ramie leaves. Thus, N fertilizer at medium rate is relatively more effective in the growth of ramie and biomass production.

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