铝胁迫下不同耐铝型桉树无性系根和叶抗氧化特征的差异

Al stress with lipid peroxidation and antioxidant enzyme activities in eucalyptus roots and leaves

为了阐明不同桉树无性系对铝的抗逆性生理响应机制,采用室内水培法,以广西区2个桉树无性系耐铝型巨尾桉9号Eucalyptus grandis×E.urophylla No.9(记为G9)和铝敏感型尾叶桉4号E.urophylla No.4(记为G4)为研究对象,在4.4 mmol·L-1铝离子浓度下处理24 h(以pH 4.0,0.5 mmol·L-1氯化钙为对照),从根系及叶片内细胞膜透性(CMP),丙二醛(MDA)质量摩尔浓度及过氧化氢酶(CAT),多酚氧化酶(PPO),超氧化物歧化酶(SOD),抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)等抗氧化酶活性方面探讨了铝胁迫下供试苗木的耐铝机制。采用SPSS21.0软件分别对根和叶中G9和G4的各测定指标进行单因素方差分析和Duncan多重比较。根细胞膜透性、丙二醛质量摩尔浓度均显著(P<0.05)高于叶,铝对2个桉树无性系苗木的毒害主要表现在根部。在4.4 mmol·L-1铝离子处理下,G4根相对电导率与丙二醛质量摩尔浓度最高,分别为48.8%,11.5μmol·g-1,而G9根内过氧化氢酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶活性极显著(P<0.01)大于G4,且G9根过氧化氢酶活性比相应对照增加145.0%,G4根过氧化氢酶活性比相应对照仅增加43.0%,过氧化氢酶在G9根中对铝毒害的缓解起到了更为重要的作用。G9清除活性氧能力较G4强,表明耐铝型桉树对铝毒害具有较好的适应能力。

Eucaplytus is the main timber tree species in south China with enrichment of aluminum(Al) in soil,but the physiological mechanisms of Al tolerance in eucalyptus trees is not well understood. To clarify the physiological response mechanism of Al resistance of eucalyptus, seedlings of the two eucalyptus genotypes(Eucalyptus grandis × Eucalyptus urophylla No.9, Al-resistant type, designated G9; E. urophylla No.4, Al-sensitive type, designated G4) were grown for 24 hours in 0.5 mmol·L-1Ca Cl2solutions(pH 4.0)containing 0 and4.4 mmol·L-1Al respectively. The indexes of plant stress resistance were measured by cell membrane permeability(CMP), malondialdehyde content(MDA), catalase activities(CAT), polyphenol oxidase(PPO), superoxide dismutase(SOD), ascorbate peroxidase(APX), and glutathione reductase(GR) in the roots and leaves.The significance of data was analyzed with one-way Anova and Duncan multiple comparison by SPSS 21.0 system. The contents of CMP and MDA in the roots were significant higher(P<0.05) than those in the leaves indicating that Al toxicity mainly happened in the roots of the two eucalyptus genotypes. With 4.4 mmol·L-1of Al stress in the roots of G4, the highest relative electrical conductivity was 48.8% and MDA content was 11.5μmol·g-1. CAT, APX, and GR activities in roots of G9 were extremely significant higher(P<0.01) than G4.CAT play an important role in the detoxification of reactive oxygen species in Al-tolerant eucalyptus clone, because it rose by 145% in the roots of G9 in response to Al treatment, only rose by 43% in G4. Conclusively,the Al-resistant eucalyptus genotype G9 was adapted to Al toxicity with active physiological characteristics to remove reactive oxygenresistant.