短期菲胁迫对大豆幼苗超氧化物歧化酶活性及丙二醛含量的影响

研究了不同浓度(0-200μg.g^-1)菲胁迫和恢复培养后大豆幼苗生长、超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量的变化．结果表明，200μg.g^-1菲处理5d后大豆幼苗生长受到抑制，但幼苗恢复培养后经短暂停滞期后仍可恢复生长．菲污染对大豆幼苗SOD活性变化的剂量—效应关系的作用形式比较复杂，胁迫2d时为线性关系，胁迫5d和8d时为抛物线型．在菲处理前期(2d)，幼苗SOD活性被100和200μg.g^-1菲显著诱导[分别为对照的1．15倍(P＜0．05)和1．26倍(P＜0．01)]．菲暴露8d时，SOD活性显著降低，200μg.g^-1菲处理组SOD活性为对照的88％(P＜0．05)．菲处理5d后恢复培养2d和4d，50和100μg.g^-1菲处理组幼苗SOD活性得到恢复，而200μg.g^-1菲处理组幼苗SOD活性仍明显高于对照(P＜0．05)．试验亦反映出，100和200μg.g^-1菲处理5d和8d，幼苗MDA含量均比对照显著增加(P＜0．05和P＜0．01)．可以认为，SOD活性可作为大豆幼苗遭受短期菲胁迫的生物标记物．

Effect of short-term phenanthrene stress on SOD activities and MDA contents in soybean (Glycine max) seedlings

Growth of soybean (Glycine max) seedlings, changes of superoxide dismutase (SOD) activities, and malonyldialdehyde (MDA) contents were researched during different concentration phenanthrene stress and following recovery from stress. The results showed that seedling growth was interrupted after 5 d in 200 micrograms.g-1 phenanthrene treatment. However, during the period of recovery, growth was restored, although there was a delay in returning to control levels. The dose-related response of SOD activities were observed in manner of linear for 2 d and of parabola for 5 d and 8 d at 50-200 micrograms.g-1 phenanthrene. SOD activities of seedling were significantly induced by 100 and 200 micrograms.g-1 phenanthrene for 2 d (P < 0.05 and P < 0.01), while declined significantly under phenanthrene stress for 8 d, and was 88% of control at 200 micrograms.g-1 phenanthrene (P < 0.05). When releasing soybean seedlings from phenanthrene stress for 5 d to clear tap water for 2 d or 4 d, their SOD activities at 50 and 100 micrograms.g-1 phenanthrene recovered towards control level, while a significant increase in SOD activities was observed at 200 micrograms.g-1 phenanthrene (P < 0.05). The experiments also revealed that a significant increase of MDA contents in seedlings occurred after 5 d and 8 d in 100 and 200 micrograms.g-1 phenanthrene treatment (P < 0.05 and P < 0.01), which suggested that the membrane systems were damaged by phenanthrene stress. All of the above results showed that SOD activities of soybean seedling might be suitable to be the biomarkers of phenanthrene stress.