镉、锌复合胁迫对银中杨化学防御的影响

Effects of Cd-Zn combined stress on chemical defense of Populus alba ‘Berolinensis’

【目的】探究镉(Cd)、锌(Zn)复合胁迫对银中杨化学防御的影响。【方法】本实验将3种含量的Cd(0.5、1.5、2.5 mg/kg)和Zn(300、500、700 mg/kg),采用正交实验设计(3×3)分别复合施加到1年生银中杨生长的土壤中,在胁迫30、40和50 d后,分析各组银中杨叶片中的防御蛋白活性以及次生代谢物质的含量。【结果】在Cd、Zn复合胁迫下,银中杨叶片中防御蛋白活性以及次生代谢物质的含量均随Cd和Zn含量的增加而降低,且高含量Cd、Zn复合胁迫下的防御蛋白的活性和次生代谢物质的含量均显著低于中低含量复合胁迫(P <0.05)。其中,在Cd、Zn中高含量复合胁迫下,30、40和50 d后,苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、胰蛋白酶抑制剂(TI)、胰凝乳蛋白酶抑制剂(CI)活性、黄酮和木质素含量,与对照组差异显著(P <0.05);在Cd、Zn低含量复合胁迫下,30、40 d后的黄酮含量以及50 d后的PAL活性,也显著低于对照组(P <0.05)。【结论】Cd和Zn复合胁迫会抑制银中杨叶片内的化学防御水平,且抑制效果呈一定的浓度和时间效应。

[Objective]This study aims to investigate the effects of Cd-Zn combined stress on chemical defense of Populus alba‘Berolinensis’(PAB).[Method]Three concentrations of Cd(0.5,1.5 and2.5 mg/kg)and Zn(300,500 and 700 mg/kg)were combined and applied in an orthogonal experimental design(3×3)into the soil with one-year-old PAB seedlings.The activities of defense proteins and the contents of secondary metabolites in the PAB leaves were analyzed at 30,40 and 50 days after Cd-Zn applications,respectively.[Result]The results showed that both the activities of defense proteins and the contents of secondary metabolites in the leaves of PAB seedlings decreased with the increase of Cd-Zn concentrations.Both parameters were significantly lower under the high Cd-Zn stresses than those under the medium-low Cd-Zn stresses(P<0.05).The activities of PAL,PPO,TI,CI,and the contents of flavonoids and lignin in the PAB leaves under the high-medium Cd-Zn(combined)stresses were significantly lower than those of control(P<0.05)for all three sampling dates(30,40 and 50 days after the Cd-Zn application).Under the low Cd-Zn combined stresses,the flavonoid contents at 30 and 40 days after the Cd-Zn application and the PAL activity at 50 days after the Cd-Zn application were also significantly lower than those of control(P<0.05).[Conclusion]The above results illustrate that Cd-Zn combined stress could inhibit the chemical defense levels of the PAB leaves,and such inhibitory effects vary,to certain degrees,with Cd-Zn concentrations and exposure durations.Further studies are need to determine how the Cd-Zn combined stresses affect PAB defoliators.