Pb胁迫对路易斯安那鸢尾幼苗生长和生理生化特性的影响

采用液体培养法研究了0（CK）、200、400、600和800 mg·L-1Pb胁迫条件下路易斯安那鸢尾（Louisiana Iris）品种‘Professor Neil’幼苗生长,叶片叶绿素含量,叶片和根系的丙二醛（MDA）和脯氨酸（Pro）含量、超氧阴离子自由基（O-·2）产生速率以及超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性的变化。结果表明：随Pb质量浓度的提高,幼苗的株高、根长、叶片和根系干质量以及耐性指数总体呈逐渐下降的趋势,且总体上显著低于对照（P〈0.05）,但各处理组间差异不显著。幼苗叶片的叶绿素a和b含量均随Pb质量浓度提高而缓慢下降,但仅在800 mg·L-1Pb胁迫条件下叶绿素a含量显著低于对照（P〈0.05）,其余处理组的叶绿素a和b含量及叶绿素a/b比值均与对照无显著差异。叶片和根系的MDA和Pro含量及POD活性均随Pb质量浓度提高逐渐增加,根系的SOD活性则随Pb质量浓度提高逐渐降低;而叶片的SOD活性以及叶片和根系的CAT活性和O-·2产生速率均在200~600 mg·L-1Pb胁迫条件下随Pb质量浓度提高逐渐增加,但在800 mg·L-1Pb胁迫下均不同程度降低,表明路易斯安那鸢尾可通过体内抗氧化酶和相关物质的诱导及合成缓解低浓度Pb胁迫对其造成的毒害作用,而高浓度Pb胁迫对路易斯安那鸢尾的伤害较重。综合分析结果表明：路易斯安那鸢尾具有一定的耐Pb特性和修复Pb污染水体的潜能。

Effect of Pb stress on growth and physiological-biochemical characteristics of Louisiana Iris seedling

Changes of seedling growth,chlorophyll content in leaf,contents of malondialdehyde（ MDA）and proline（ Pro）,superoxide anion free radical（ O-·2） production rate and activities of superoxide dismutase（ SOD）,peroxidase（ POD） and catalase（ CAT） in leaf and root of Louisiana Iris ‘Professor Neil＇seedling under stress condition with 0（ CK）,200,400,600 and 800 mg·L- 1Pb were researched by solution culture method. The results show that with enhancing of Pb concentration,generally,height,root length,dry weights of leaf and root and tolerance index of seedling appear gradually decreasing trend,and are significantly lower than those of the control（ P〈0. 05） as a whole,but there is no significant difference among treatment groups. With enhancing of Pb concentration,contents of Chla and Chlb in leaf of seedling decrease gradually but only Chla content under 800 mg · L- 1Pb stress is significantly lower than that of the control（ P〈0. 05）,differences in contents of Chla and Chlb and ratio of Chla / Chlb between other treatment groups and the control all are not significant. With enhancing of Pb concentration,contents of MDA and Pro and POD activity in leaf and root all increase,and SOD activity in root decreases. While SOD activity in leaf and CAT activity and O-·2production rate in leaf and root all increase with enhancing of Pb concentration under 200- 600 mg·L- 1Pb stress,but those decrease with different degrees under 800 mg·L- 1Pb stress,meaning that Louisiana Iris can relieve the toxic action caused by low concentration of Pb stress via induction and synthesis of antioxidant enzymes and related substances in vivo,while damage of high concentration of Pb stress to Louisiana Iris is serious. The comprehensive analysis result indicates that Louisiana Iris possesses a certain resistance to Pb and the potential ability to repair water polluted by Pb.