2种鼠尾草对模拟酸雨胁迫的耐受性比较及其生理机制研究

为探究2种具有较高药用和观赏价值的鼠尾草对酸雨的耐受性及其生理机制，以美丽鼠尾草(Salvia meiliensis S.W.Su)和贵州鼠尾草(S. cavaleriei Lévl.)为试验材料，分析了2种鼠尾草在不同pH(6.8、5.6、4.5、3.5和2.5)模拟酸雨胁迫下伤害等级、叶绿素含量、抗氧化酶活性以及丙二醛和有机渗透调节物质含量的变化。结果显示：模拟酸雨对美丽鼠尾草的伤害程度高于贵州鼠尾草；随pH的下降，2种鼠尾草叶片叶绿素a、b和总含量逐渐降低，但贵州鼠尾草叶片叶绿素a、b和总含量高于美丽鼠尾草，并以较高的叶绿素a/b适应模拟酸雨胁迫；2种鼠尾草在模拟酸雨胁迫下产生了适应性反应，表现为叶片可溶性糖、可溶性蛋白和脯氨酸含量以及超氧化物歧化酶和过氧化物酶活性的升高，但这一适应性反应被降低的过氧化氢酶活性严重削弱；模拟酸雨胁迫下，贵州鼠尾草叶片SOD、POD和CAT活性均高于美丽鼠尾草，叶片MDA含量低于美丽鼠尾草。研究表明，尽管美丽鼠尾草渗透调节能力很强，但其抗氧化酶活性、叶绿素含量和叶绿素a/b都低于贵州鼠尾草，使其膜脂过氧化程度较高、对光能的吸收和转化效率较低，是其对模拟酸雨的耐受性低于贵州鼠尾草的重要原因。

Comparison of Tolerance between Two Salvia Plants to Stress of Simulated Acid Rain and Study of the Physiological Mechanisms

To investigate the different tolerances to simulated acid rain between two Salvia with high medicinal and ornamental value and the corresponding physiological mechanisms, S. meiliensi and S. cavaleriei were used as experimental materials to analyze the variations in their damage grades, chlorophyll contents, antioxidase activities as well as the contents of malondialdehyde (MDA) and organic osmotic regulation substances under the stresses of simulated acid rain (pH 6.8, 5.6, 4.5, 3.5 and 2.5). The results showed that S. meiliensis suffered severer damage from simulated acid rain than S. cavaleriei. Total chlorophyll, chl a and chl b contents in the leaves of two Salvia declined gradually with the decrease in pH. However, these three parameters in S. cavaleriei were higher than those of S. meiliensis. Moreover, S. cavaleriei could adapt to the stresses of simulated acid rain with the higher chlorophyll a/b ratio. In addition, the two Salvia could adaptively react to the stresses of simulated acid rain through increasing the soluble sugar, soluble protein and proline contents as well as superoxide dismutase (SOD) and peroxidase (POD) activities in the leaves. However, the adaptive reactions of the two Salvia were weakened severely by decreased catalase (CAT) activities in the leaves. Under the stresses of simulated acid rain, SOD, POD and CAT activities in the leaves of S. cavaleriei were higher than those of S. meiliensis. In contrast, MDA content in the leaves of S.cavaleriei was lower than that of S. meiliensis. Although S. meiliensis possesses a strong ability of osmotic regulation, its lower tolerance to the stresses of simulated acid rain relative to S. cavaleriei should be ascribed to its lower antioxidase activities, chlorophyll content and chl a/b, which aggravate the peroxidation of membrane lipids and reduce the absorption and transformation of light energy.