蒌蒿对镉的富集特征及亚细胞分布特点

以镉(Cd)富集植物蒌蒿(Artemisia selengensis)为试材, 采用超声波细胞破碎处理和超速离心的方法, 对蒌蒿根和叶中亚细胞水平的Cd分布状况进行研究, 同时测定Cd在蒌蒿不同器官中的富集效果。结果表明, 在30 mg·kg^–1Cd胁迫下, 蒌蒿叶片中Cd的富集浓度是根和茎中的2–3倍, 但因叶片所占植株的生物量比例较小, 其对Cd的积累量远小于茎和根; Cd在蒌蒿叶片细胞壁、胞液和细胞器中含量比为16:5:1。细胞壁固定是叶片对Cd的主要防御机制。随着Cd处理浓度的增加, 细胞壁和胞液中的Cd含量大幅上升, 但细胞器中Cd含量仍维持在较低水平。长时间和高浓度的Cd胁迫可使细胞壁解毒机制失活并诱导细胞器中的Cd含量增加, 导致植株死亡。根中液泡的Cd贮存量较大, 解毒效果显著。

Cadmium Accumulation and Subcellular Distribution in Different Organs of Artemisia selengensis

We used fractionation with cadmium (Cd) treatment to investigate the subcellular distribution of Cd in different organs of Artemisia selengensis. With 30 mg·kg^─1 Cd, Cd content was 2 to 3 times higher in leaves than in stems and roots; however, because of the smaller proportion of leaf biomass to total plant biomass, the amount of Cd in leaves was much less than that in stems or roots. Under the stress of this Cd concentration, the subcellular distribution ratio of Cd in leaves was 16:5:1 for cell walls, cytosole, and organelles. The retention of Cd in the cell walls is a major defense mechanism of leaves. The Cd content in cell walls and cytosole increased significantly with increasing additional Cd²⁺, but Cd content in organelles was still low. The stress of long-term Cd exposure or high Cd concentration causes serious harm or even death to a plant. A large amount of Cd is deposited in root vacuoles, for a detoxification effect for Cd stress.