多蒴灰藓（苔藓植物门：藓纲）对短期极端温度的生理响应

近年来，藓类植物作为一类模式植物，在分子生物学、抗性生理学研究中受到重视，因此，开展逆境条件下藓类植物渗透调节物质和膜保护系统相关指标变化的研究，将为了解藓类植物对逆境条件适应的生理机制提供基础资料。多蒴灰藓（Hypnum fertile Senden.）分布广泛，生境多样，本文研究了低温(5℃)和高温(40℃和60℃)在不同胁迫时间(0、1、2、4、6、8h)下多蒴灰藓体内可溶性糖、游离脯氨酸、丙二醛（MDA）含量和过氧化物酶（POD）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性的变化，以期了解多蒴灰藓对不同温度条件的适应能力和响应的生理机制。结果表明：在5℃低温处理下，随处理时间延长，多蒴灰藓的可溶性糖含量逐渐增加，在高温处理下，呈现先升高后降低的趋势；游离脯氨酸、MDA在低温和高温胁迫下随处理时间延长都逐渐升高。CAT在5℃低温处理下活性逐渐升高，在40℃高温处理下先升高后降低，在60℃高温处理下则迅速降低，6 h后酶完全丧失活性。SOD的活性在5℃低温处理下随处理时间延长逐渐降低，在高温处理下则表现出先升高后降低趋势，40℃高温胁迫下6 h达到最大值，60℃胁迫下0.5 h达到最大值。POD在5℃和40℃处理下活性随处理时间延长逐渐升高，在60℃高温处理下则先升高后降低。这些结果表明，多蒴灰藓适生于20℃左右的温度条件下，60℃高温对多蒴灰藓的伤害明显，与高温相比，多蒴灰藓更适合生长于低温环境；多蒴灰藓通过增加游离脯氨酸以提高对温度逆境的适应；POD和CAT在多蒴灰藓抵御低温胁迫时可能起着主要作用，而SOD则在其抵御高温胁迫时起一定的作用。

Physiological Responses of Hypnum fertile Sendtn.(Musci:Hypnaceae)to Short-term Extreme Temperature Stress

Mosses attracted more and more attention in the fields of molecular biology and stress physiology as mode plants. Researches on osmolytes and antioxidant enzymes of mosses under stress conditions will provide base materials to understand their physiological mechanisms to stress conditions. Hypnum fertile Sendtn. a moss species with a wide range of habitats and geographical distributions, was treated under 5, 40 and 60℃ for 0.5, 1, 2, 4, 6 and 8 h, respectively. The contents of soluble sugar, free proline, MDA and the activities of SOD, POD, and CAT were determined. The main results were: 1) the content of soluble sugar increased with stress time under 5℃, while first increased and then decreased under 40 and 60℃; 2) the contents of free proline and MDA both increased with stress time under 5, 40 and 60℃；3) the activity of CAT gradually increased under 5℃, first increased and then decreased under 40℃, while declined rapidly and completely lost activity after 6h treatment under 60℃; 4) the activity of SOD decreased with the time under 5℃, while first increased and then declined under 40 and 60℃; 5) the activity of POD both increased under 5 and 40℃, while first increased and then decreased under 60℃. Our conclusions were: 1) the damage of low temperature (5℃) to H.fertile is less than high temperature (40 and 60℃), namely H.fertile is suitable to distribute in lower temperature environments; 2) Free proline enhanced the tolerance of H.fertile to both lower and higher temperature stresses; 3) POD and CAT might play a role in the adaptation of H.fertile to lower temperature environment, while SOD to higher temperature environment.