渗透胁迫对绵刺(Potaninia mongolica Maxim.)嫩枝保护酶活性的影响

分别用不同浓度的 Ｐ Ｅ Ｇ（ Ｍ Ｗ ６０００）对当年生绵刺嫩枝进行渗透胁迫处理，测定其超氧化物歧化物（ Ｓ Ｏ Ｄ）、过氧化氢酶（ Ｃ Ａ Ｔ）的活性和丙二醛（ Ｍ Ｄ Ａ）含量的变化。结果表明：绵刺嫩枝在渗透份胁大于－ ２．０ Ｍ Ｐａ 迫条件下，能维持较高的 Ｓ Ｏ Ｄ 活性，脂质过氧化作用较弱，膜系统基本完整； 渗透胁迫小于－ ２．０ Ｍ Ｐａ。 Ｓ Ｏ Ｄ 活性明显下降，脂质过氧化作用加强，膜透性增加。 Ｍ Ｄ Ａ 含量与 Ｓ Ｏ Ｄ 活性呈负相关关系（ｒ＝ － ０９４２１７）； Ｃ Ａ Ｔ 的活性随渗透胁迫强度增大而逐渐增强，达到一个峰值（－ ２．５ Ｍ Ｐａ）后，呈现下降趋势。说明绵刺嫩枝中 Ｃ Ａ Ｔ 和 Ｓ Ｏ Ｄ 活性具很强的抗水分胁迫能力。

EFFECT OF OSMOTIC STRESS ON ACTIVITIES OF PROTECTIVE ENZYMES OF TENDER BRANCHES OF POTANINIA MONGOLICA MAXIM.

The tender branches of Potaninia mongolica Maxim.were treated with PEG(6000) solutions at different concentrations(0,-0.5,-1.0,-1.5,-2.0,-2.5,-3.0 MPa).Above -2.0 MPa,the activities of supcroxide dismutase (SOD) (Fig.1) kept at higher levels.Malondialdehyde (MDA),substance toxic to the membrane,were maintained at low levels (Fig2).The increases of osmotic potential were accompanied by decreases of SOD activity and increases of MDA content.The relation of MDA and SOD was negative correlation (r=-0.94217).The increases of osmotic potential were accompanied by increases of catalase (CAT) above -2.5 MPa and decreases under -2.5 MPa. There evidences showed the Potaninia mongolica Maxim.tender branches have a powerful ability to adapt drought stress.