马缨丹对铜的生理响应及亚细胞分布特征

Physiological response and subcellular distribution of copper in Lantana camara L.

通过盆栽试验，分析了不同浓度铜处理下马缨丹（LantanacamaraL．）的生物量、抗氧化酶活性及其对铜的吸收、转运和亚细胞分布。结果表明：低于600mg·kg-1的铜处理下，马缨丹根、茎、叶的生物量分别较对照增加了6％～23％、4％-29％、6％-19％；而高于此浓度时，根系生物量无显著降低，但茎和叶的生物量分别较对照下降了26％-39％和19％-37％。铜处理下，其体内铜含量仅为12．45-59．17mg。kg-1,且根系中铜含量均高于地上部，根系抑制了铜的吸收和转运；亚细胞分布研究表明，铜主要固定于根的可溶性部分（37％-64％）和茎、叶的细胞壁（40％-43％、29％-38％），具有保护细胞器的分布特征。此外，低于600mg·kg-1的铜处理下，其根系和叶片中SOD、CAT、APX的活性显著高于对照，植株能够缓解低于600mg·kg-1铜处理诱导的氧化胁迫；而高于此浓度时，叶片中POD、CAT、APX活性显著下降，抗氧化能力减弱，叶片受到氧化胁迫伤害，但根系受到的影响较小。因此，马缨丹是一种铜耐性植物，且根部的耐性强于地上部，其主要耐性机制是根系对铜的限制、可溶性部分和细胞壁对铜的固定及抗氧化酶对活性氧物质的清除。

Lantana camara L. is verbenaceae dwarf shrub that grows normally in copper（Cu） polluted soils. However, its Cu-tolerant mech- anisms are not clear yet. In this study, a pot experiment was conducted to investigate its growth, antioxidant enzyme activities and Cu uptake, translocation and subcellular distribution. Compared with the control, all root, stem and leaf biomass increased by 4%-29% in soils with Cu up to 600 mg·kg-1, whereas the shoot biomass decreased by 19%-39% when soil Cu was higher than 600 mg·kg-k The concentrations of Cu in whole plant ranged from 12.45 mg·kg-1 to 59.17 mg·kg-1, with higher in roots than in shoots. Between 37%~64% of root Cu was stored in the soluble fraction of roots, whereas 40%-43% and 29% ~38% of Cu in stems and leaves were stored in their cell walls, respectively. The superoxide dismutase, catalase and ascorbate peroxidase activities in roots and leaves enhanced with increasing soil Cu up to 600 mg·kg-1, indicating that L. camara is able to relieve the oxidative stress; However, these activities displayed decreases in leaves but little change in roots when the soil Cu was greater than 600 mg· kg-1. These results showed that the tolerance of L. camara to Cu was weaker in leaves than in roots. The tolerance mechanisms might include root restriction, soluble fraction and cell wall immobilization, and antioxidant system responses.