铜胁迫对甘蔗生长及抗氧化酶活性的影响

Effects of copper stress on growth and antioxidant enzymes in sugarcane

关键词:  甘蔗, 铜处理, 相对电导率, 叶绿素, 氧化胁迫

Key words:  sugarcane, copper treatment, relative electrical conductivity, chlorophyll, oxidative stress

摘要:

甘蔗是重要的糖能兼用植物,同时也是潜在的重金属土壤修复植物。为了探明甘蔗对铜胁迫的生理响应,该研究采用营养液培养的方法分析了铜胁迫对甘蔗生长、叶片相对电导率、叶绿素含量及根系抗氧化酶活性等的影响。结果表明:甘蔗地上部分生物、叶绿素含量随铜浓度增加而下降,地上部分铜含量和叶片的相对电导率则随铜浓度增加而提高。根系的丙二醛(MDA)含量在胁迫24 h开始发生显著的变化,在400 μmol·L^-1铜处理下比对照显著增加了25.5%,随着胁迫时间的延长,丙二醛含量增加幅度上升。到胁迫72 h,100 μmol·L^-1铜处理的MDA含量也显著的提高。根系SOD、POD和CAT酶活性在胁迫24 h开始发生显著的变化,但不同酶活性变化存在差异。SOD酶活性除了在胁迫的72 h随铜浓度增加而提高,其他时间表现为在100 μmol·L^-1铜处理下活性下降,随着铜浓度继续增加SOD酶活性提高,到400 μmol·L^-1铜处理SOD酶活性又出现下降。POD酶活性在处理的24、48和72 h表现为随浓度增加先提高后下降的趋势,但在处理7 d时随铜浓度增加而提高。CAT酶活性随着浓度的升高和胁迫时间的延长而下降,到了胁迫的第7天,三个铜处理下CAT酶活性分别下降了89.98%、96.88%和98.50%。由此可见,铜胁迫严重影响甘蔗的生长,较短时间的处理就已经引起了甘蔗根系的氧化胁迫,根系中SOD、POD和CAT酶活性的变化在甘蔗对抗铜引起的氧化胁迫中起到重要作用。

Abstract:

Sugarcane is the most important sugar and energy crop. It is also the potential plant for remediation of high metal-polluted soil. To evaluate the physiological response of sugarcane to copper(Cu)stress, the weight of sugarcane, content of chlorophyll, relative electrical conductivity in leaves and activities of antioxidant enzymes in roots were examined by hydroponics. The results revealed that the growth of sugarcane inhibited by Cu stress. The weight of shoot and content of chlorophyll decreased with the increase of Cu content in nutrient solution, while the copper content in shoot and relative electrical conductivity in leaves increased in response to copper stress. The malonaldehyde(MDA)content was increased significantly by 25.5% under 400 μmol·L^-1 treatment at 24 h when compared with the control, and then the rate increase raised with the prolonging of treatment time. The MDA content increased notably after 72 h under 100 μmol·L^-1 Cu treatment. The activities of SOD, POD and CAT changed significantly after 24 h treatment, but notable differences were found among different enzymes. The activities of SOD firstly dropped under 100 μmol·L^-1 treatment, and then increased with the increase of Cu content in solution under 200 μmol·L^-1 treatment, following with decrease of enzyme activities under 400 μmol·L^-1 treatment at 24 h, 48 h and 7 d. However, the activities of SOD increased with the increase of Cu content in solution at 72 h. The activities of POD increased with the increase of Cu content in solution, following with decline of enzyme activities under high content of Cu treatment at 24, 48 and 7 h except at 72 d. The activities of CAT decreased significantly with the increase of Cu content in solution and with the prolonging of stress time. The activities of CAT declined by 89.98%, 96.88% and 98.50% under three Cu treatments, respectively on the seventh day. Thus, the growth of sugarcane was greatly inhibited by copper stress and the change of SOD, POD and CAT activities might play an important role in alleviating oxidative stress caused by Cu stress.