土壤Cd胁迫对三七生长和根系DNA损伤及抗氧化酶活性的影响

采用盆栽实验法,研究了土壤中添加0.0(对照)、0.1、0.3、0.6、1.0、3.0、6.0、10.0和30.0 mg·kg-1Cd对三七〔Panax notoginseng(Burk.)F.H.Chen〕生长和抗氧化酶活性的影响,并采用彗星实验对Cd胁迫条件下三七根尖细胞的DNA损伤进行了分析。结果显示:随土壤Cd添加量增加,三七的成活率、株高、单株复叶数和单株叶面积以及单株根、茎和叶片的干质量及鲜质量总体上呈先升高后降低的趋势;其中,各处理组三七植株的成活率和单株复叶数均高于对照,而株高和单株叶面积则在Cd添加量较低的条件下高于对照、在Cd添加量较高的条件下低于对照;单株根、茎和叶的鲜质量及干质量在Cd添加量30 mg·kg-1条件下均小于对照但差异不显著。随Cd添加量的提高,三七根系中SOD和CAT活性呈先上升后下降、再上升再下降的变化趋势,而POD活性总体上逐渐升高;其中,Cd添加量0.6、1.0、3.0和30.0 mg·kg-1处理组的SOD活性极显著或显著低于对照,而各处理组的POD和CAT活性总体上均高于对照且在Cd添加量1.0~30.0 mg·kg-1条件下与对照有极显著差异。彗星实验结果表明:各处理组三七根尖细胞的彗尾长、尾部DNA相对含量和Olive尾矩均有差异,其中,在Cd添加量较高的条件下各指标均高于对照但差异均不显著。研究结果显示:在较低水平的土壤Cd胁迫条件下,三七的生长、抗氧化酶活性和根系DNA均没有受到明显伤害,而较高水平的Cd胁迫则对其生长和抗氧化酶活性有抑制作用,且根尖细胞DNA损伤也较严重。

Effect of soil Cd stress on growth,root system DNA damage and antioxidant enzyme activity of Panax notoginseng

Effect of soil with Cd adding amounts ofO. O （CK）, 0.1, 0.3, 0.6, 1.0, 3.0, 6.0, 10.0 and 30.0 mg ·kg-1 on growth and antioxidant enzyme activity of Panax notoginseng （Burk.） F. H. Chen was studied by pot experiment method, and DNA damage in root-tip cell of P. notoginseng under Cd stress was analyzed by Comet assay. Results show that with rising of Cd adding amount in soil, survival rate, plant height, compound leaf number per plant, leaf area per plant and dry and fresh weights of root, stem and leaf per plant appear the trend of first increasing and then decreasing. In which, survival rate and compound leaf number per plant of all treatment groups are higher than those of the control, while plant height and leaf area per plant are higher under low adding amount of Cd and are lower under high adding amount of Cd than those of the control. And dry and fresh weights of root, stem and leaf per plant under Cd adding amount of 30.0 mg·kg-1 are all lower than those of the control with no significant difference. With rising of Cd adding amount, SOD and CAT activities in root system appear the changing trend of ＂enhancing-reducing-enhancing-reducing＂, while overall, POD activity enhances gradually. In which, SOD activity of treatment groups with Cd adding amounts of 0.6, 1.0, 3.0 and 30.0 mg·kg-1 is extremely significant or significant lower than that of the control, while POD and CAT activities of all treatment groups are generally higher than those of the control and have extremely significant difference with the control under Cd adding amounts of 1.0-30.0 mg·kg-1. Comet assay result shows that there are some differences in tail length, tail DNA relative content and Olive tail moment in root-tip cell of all treatment groups, in which, these three indexes are higher under higher adding amount of Cd than those of the control with no significant difference. It is suggested that there is no obvious injury on growth, antioxidant enzyme activity and root system DNA of P. notoginseng under soil Cd stress with lower level, but there is an inhibitory action on growth and antioxidant enzyme activity and a serious injury on root-tip cell DNA under soil Cd stress with higher level.