玉米对Cs^+的富集能力及Cs^+对其抗氧化指标影响的研究

Accumulation Capability for Cs^+ and Effects of Cs^+ on Antioxidant Parameters in Maize

研究了玉米对不同浓度Cs+的富集差异,并探讨Cs+对玉米幼苗抗氧化指标的影响。结果表明:玉米幼苗中Cs+含量均与处理浓度和时间呈显著正相关,根是主要的富集器官,其次为茎;在20mmol/L处理28d后,根的Cs+含量分别是茎和叶的1.6和5.1倍;根、茎、叶Cs+含量分别是0.5mmol/L处理浓度的16.3、18.0和24.7倍。所有处理时期根、茎、叶转运系数和富集系数与处理时间呈显著正相关,均为茎的转运系数大于叶的转运系数,富集系数由高到低依次为根、茎、叶。对抗氧化生理指标的分析发现,随Cs+浓度的增加和处理时间的延长,玉米幼苗POD和CAT活性均表现为先应激性上升后下降的动态变化,丙二醛和过氧化氢含量均呈上升趋势,且与处理时间均呈显著正相关,这表明POD和CAT清除有害过氧化物的能力有限,高浓度时均受到一定程度的抑制,抗氧化体系在一定程度上被破坏。

The threat of radiocesium pollution has led to an increased interest in elucidating the mechanisms of this mental toxicity in organism.In this study,three-leaf stage maize（Zea mays L.cv.Chuandan No.15） seedlings raised in hydroponic culture system,were provided with a nutrient solution containing 0,0.5,1,5,10 or 20 mmol/L Cs^＋ supplied by cesium chloride（CsCl） solution.Uptake and distribution of Cs^＋ in maize seedlings leaves,stems and roots,and the effects on antioxidant characteristics were investigated after 0,7,14,21 and 28 d of the Cs^＋ treatment.The results demonstrate that various organs of maize seedlings show different abilities of accumulation on Cs^＋.Cs^＋ contents are up to 1.6-fold and 5.1-fold higher in roots as compared to leaves and stems（following 28 days＇ exposure to 20 mmol/L Cs^＋）,and Cs^＋ contents of roots,stems and leaves are up to 16.3-fold,18.0-fold and 24.7-fold higher than exposure to 0.5 mmol/L Cs^＋,respectively.The root is a primary Cs^＋ accumulation organ,which is higher than that of stem and leaf.Both transfer factor and bioconcentration factor show significantly positive relationship with treatment time.For antioxidant parameters analysis,the activities of peroxidase（POD,EC 1.11.1.7） and catalase（CAT,EC 1.11.1.6） increase at first,and then decline with increasing concentration of applied Cs^＋ and also with the duration of exposure time.Contents of hydrogen peroxide（H2O2） and malondialdehyde（MDA）,however,obviously increase with the increasing of the Cs^＋ concentration and exposure time.The capacity of clearing up the harmful peroxide for POD and CAT is limited,and then POD and CAT activities are inhibited under higher Cs^＋ concentration,and antioxidant system is likely impaired in some way.