向日葵对锶的富集特征与耐受机制研究

为探明向日葵(Helianthus annuus L.)对金属锶的富集特征和耐受机制,本试验施加不同浓度锶(25、150、750和1500 mg·kg-1)土培处理30 d,研究了向日葵幼苗体内锶的富集和分配特征及对植物生长和膜脂过氧化产物MDA(丙二醛)含量、SOD(超氧化物歧化酶)、POD(过氧化物酶)、CAT(过氧化氢酶)活性的影响.结果显示:(1)向日葵幼苗的根长、株高、根生物量和地上生物量随着土壤中金属锶浓度的升高呈先增加后降低的趋势;(2)向日葵的根、茎、叶均能富集金属锶,不同器官表现为根叶茎.向日葵的生物富集系数与不同器官金属锶富集浓度呈显著负相关,且根部金属锶浓度与富集系数的相关性最强;(3)MDA含量随着锶浓度升高呈先减少后增加的趋势,而抗氧化酶SOD、POD和CAT活性均随着锶浓度升高呈先增加后减少的趋势.SOD和POD活性在高浓度金属锶处理中受到了抑制,而高水平的CAT活性表明向日葵清除活性氧的能力增强.以上结果表明,向日葵的根、茎、叶均能积累锶,根部的富集能力最强,且根部的抗氧化酶系统对金属锶胁迫更为敏感,其中较高的CAT活性表明在向日葵耐受锶胁迫机制中起到关键作用.此研究为金属锶污染土壤的植物修复以及向日葵对锶的耐受机制提供理论依据.

Strontium accumulation characteristics and tolerance mechanisms in Helianthus annuus L.

This study was aimed to investigate the strontium accumulation patterns and tolerance mechanisms of sunflowers (Helianthus annuus L.). Sunflower seedlings were chosen as experimental materials, with four concentrations of strontium (25,150,750 and 1500 mg·kg^-1) added in soil. Plants were cultivated for 30 days. The strontium accumulation and distribution characteristics, growth index, POD, SOD and CAT activity of sunflowers were determined under four strontium concentrations. The results showed1 under different strontium concentrations, root length, plant height and plant biomass of sunflower seedlings rose first and reduced later as the strontium concentrations in soils; 2 the root, stem and leaf of sunflower could absorb a certain amount of strontium, whereas accumulation pattern showed a significant difference between organs, with root > leaf > stem. Meanwhile, the strontium accumulation of organs showed significant differences under strontium treatments, and increased with the strontium concentrations. The bioconcentration factors of sunflower showed significantly negative correlation with strontium concentration of organs, while the strongest correlation was found in root; 3 the MDA content rose first and reduced later as strontium concentration increased, whereas the POD, SOD and CAT activity showed an inverse pattern as strontium concentration increased. CAT activity in the highest strontium concentration (1500 mg·kg^-1) was significantly higher than that in the control. The results showed that the root, stem and leaf of sunflower could accumulate strontium, and the root was the strongest enrichment organ, which was more sensitive to strontium stress. Moreover, CAT played a key role in the strontium resistance mechanism of sunflower. This study provided theoretical basis for the phytoremediation of strontium contaminated soils and the tolerance mechanism of sunflower to strontium.