镉胁迫对矮牵牛种子萌发、幼苗生长及抗氧化酶活性的影响

Effects of Cd Stress on the Seed Germination,Seedling Growth and Activities of Antioxidant Enzymes in Petunia hybrida

采用营养液培养的方法研究了不同浓度镉Cd(0、1、2和4 mmol.L-1)处理对矮牵牛(Petunia hybrida)种子萌发、幼苗生长及生理特性的影响。结果发现:与对照相比,较低浓度(1 mmol.L-1)Cd处理下矮牵牛种子萌发和幼苗生长均显著被抑制,当Cd浓度增至4 mmol.L-1时完全抑制了矮牵牛种子的萌发。Cd胁迫在低浓度时激活矮牵牛幼苗叶片过氧化物酶(POD)、过氧化氢酶(CAT)活性,而高浓度产生抑制效应;抗坏血酸过氧化物酶(APX)和超氧化物歧化酶(SOD)活性与对照相比均显著升高,丙二醛(MDA)含量无显著变化。不同浓度的乙二胺四乙酸(EDTA)的加入使4 mmol.L-1Cd胁迫下矮牵牛幼苗叶片POD和APX活性增加,但不影响SOD和CAT活性;此外,6 mmol.L-1EDTA使Cd胁迫下矮牵牛幼苗叶片中MDA含量增加。结果表明,Cd胁迫抑制矮牵牛种子萌发和幼苗生长,却使幼苗叶片POD、CAT和APX活性增加,EDTA的加入能够进一步提高Cd胁迫幼苗POD和APX活性。因此,矮牵牛幼苗在Cd胁迫下具有较强的抗氧化损伤的能力。

Effects of different cadmium（Cd） concentrations（0,1,2 and 4 mmol·L-1） on the seed germination,seedling growth and physiological property of Petunia hybrida were studied.In comparison with the control,seed germination and seeding growth exhibited a significant decrease at low level of Cd2＋ concentration（1 mmol·L-1）,and these factors were all completely restrained at high concentration（4 mmol·L-1）.Compared to the control,the activities of peroxidase（POD） and catalase（CAT） were enhanced in P.hybrida seedings exposed to low Cd concentrations but inhibited at higher concentrations;the activities of ascorbate peroxidase（APX） and superoxide dismutase（SOD） could be increased in response to different Cd concentrations,no significant change in the malonaldehyde（MDA） content was observed.Ethylene-aminetetraacetic acid（EDTA） could stimulate the activities of POD and CAT in P.hybrida seedlings exposed to 4 mmol·L-1 Cd treatment,and MDA content was also enhanced when seedlings were treated with 4 mmol·L-1 Cd in the presence of 6 mmol·L-1 EDTA.In conclusion,these results indicate that Cd stress significantly inhibit P.hybrida seed germination and seedling growth,but stimulate the activities of POD,CAT and APX in the leaves of seedlings;the application of EDTA further enhance the activities of POD and APX in Cd-treated P.hybrida seedlings.Therefore,higher activities of antioxidative enzymes may protect P.hybrida seedlings against Cd-induced oxidative change.