中文摘要：

发菜是一种陆生固氮蓝藻，具有强烈的旱生生态适应性。对干旱胁迫条件下发菜超微结构和抗性生理进行了研究。结果表明：随着干旱胁迫加重，发菜细胞大小和细胞壁厚度变化不显著，胶质鞘趋于紧密，类囊体排列趋于紊乱，多角体变得模糊不清甚至消失，糖原颗粒数目减少，但结构颗粒数目没有明显变化。随着干旱胁迫的加重，发菜SOD、CAT活性呈先升高再下降趋势，SOD在含水量为120％时达到高峰；CAT活性在含水量为445％时达到高峰；MDA，氧自由基随着干旱胁迫加重，其含量呈上升趋势；H2O2含量随干旱胁迫加重呈先升高再下降趋势，在含水量为120％时达到峰值。干燥储存1年的发菜与恢复活性的发菜有明显差异性，其SOD、CAT活性较低、MDA、H2O2含量较少，但是氧自由基含量最高。研究结果对深入研究发菜的耐旱机理奠定了基础。

英文摘要：

Nostoc flagelliforme is a terrestrial nitrogen-fixing cyanobacteria, which has strong xeric ecological a- daptability. The ultrastructure and physiological resistance of N.flagelliforme under drought stress were studied. The results showed that With increasing drought stress, the cell size and wall thickness were not significantly changed, the sheath tended to be shrunk, the arrangement of thylakoids tended to be disordered, and the poly- hedron tended to be blurred and even disappeared, the amount of glycogen granules were decreased, but the a- mount of structural granules did not change significantly. SOD and CAT activities were firstly increased and then decreased, SOD activity reached the peak when the content of water reached 120%, but CAT activity reached the peak when the content of water reached 445%. With the increasing of drought stress, MDA content and oxy- gen free radical level were increased, H2 O2 content firstly increased and then declined, it reached the peak when water content reach 120%. There were obvious differences between N.flagelliforme which dried storage for 1 year and resuscitative N.flagelliforme, the SOD and CAT activities, MDA and H2 02 contents were all lower than those of resuscitative N. flagelliforme, but oxygen free radical level reached the highest value. The results laid the foundation for the further studies on tolerance mechanism in N. flagelliforme.