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ABSTRACTThe role of exogenous methyl jasmonate (MeJA) in alleviating drought stress was investigated on Huangguogan. Except for intercellular CO2concentration, MeJA had little effect on net photosynthetic rate, stomatal conductance, and transpiration rate under drought stress. Compared with drought stress, MeJA significantly alleviated the decrease of chlorophyll content. However, chlorophyll a/bratio was significantly increased. MeJA significantly increased proline and soluble sugar contents, significantly decreased the O2−·and H2O2levels, and increased SOD and POD activities. In addition, the MDA content of drought stress was the highest of all treatments. MeJA significantly reduced MDA content in drought-stressed Huangguoganleaves. Although the Ascorbic acid (AsA) contents of 500 and 1000 mg L−1MeJA treatments were lower than that of 250 mg L−1MeJA, but all concentration of MeJA treatments delayed the decline of AsA content. Therefore, MeJA could induce drought stress tolerance by increasing the osmotic adjustment substances and antioxidant activities.