The activities and isoforms of superoxide dismutase peroxidase(POD)and catalase(CAT),as well as the contents of pmline,soluble protein(SOD)and malondialdehyde(MDA)in plantlets of Broussonetia papyrifera subjected to salt stress treatments 0f 50,75,100,125 and 150 mmol·L-1NaCl were studied.Our results demonstrated that soluble protein content increased with NaCl concentration at low level of NaCl concentration,and it decreased when NaCl concentration exceeds 100 mmol.L-1.SOD activity 8howed a slight decrease in low concentration of NaCl and then an increase with further increase in NaCl concentration.Moreover,the isoforms of SOD were affected by salt stress.POD exhibited a similar trend in enzyme activity as compared to SOD,However,the POD isoforms were minimally affected by NaCl treatment.CAT activity Was increased by salt treatrnent.Moreover,proline contents markedly increased while the contents of MDAWas increasedat first and decreased subsequently in response to salt stress.%构树组培苗在50,75,100,125和150 mmol-L-1 NaCl胁迫下,SOD,POD,CAT活性和这3种抗氧化酶同工酶谱的变化情况,以及不同浓度NaCI对可溶性蛋白、脯氨酸和MDA含量的影响.结果表明:NaCI浓度小于100mmol.L-1时可溶蛋白含量升高,随着NaCl浓度的增加可溶蛋白含量降低.低浓度NaCl使SOD活性略有降低,随着浓度升高活性逐渐增强;SOD同工酶谱在NaCI胁迫后变化明显.POD活性变化趋势与SOD相似,而POD同工酶谱略有变化.CAT活性明显提高,而其同工酶谱变化甚微.此外,NaCl胁迫还导致脯氨酸含量明显升高,而MDA含量呈现先升高后降低的趋势.
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