镧对汞胁迫下矢竹叶片生理反应的调节

Regulating Effects of Lanthanum on Physiological Response of Pseudosasa japonica Leaf to Mercury Stress

为了研究稀土镧对汞胁迫下林木叶片伤害的缓解效应,以矢竹为材料,采用离体处理方法,对不同浓度汞胁迫及一定浓度外源镧稀土处理条件下矢竹叶片部分生理生化指标进行测定。试验表明:0.25mg.L-1镧稀土处理可以显著抑制低浓度(10mg.L-1)汞胁迫下叶片细胞质膜透性的增加,蛋白质、叶绿素含量的下降,有效缓解叶片在胁迫下的伤害;中等浓度(50mg.L-1)汞胁迫下,镧的调节作用不明显,而高浓度(200mg.L-1)汞胁迫下镧处理则起反作用,镧与汞产生协同效应。镧对汞胁迫伤害的缓解效应除了维持质膜、大分子物质结构以及保护酶(SOD、POD)系统活性的稳定外,还可能与多胺代谢变化有关,镧能显著促进10mg.L-1汞胁迫下叶片内源腐胺(Put)、亚精胺(Spd)和精胺(Spm)含量的增加,并与SOD活性的变化呈正相关,而与POD活性变化呈负相关。多胺含量的升高可能是镧稀土缓解汞胁迫伤害作用的方式之一,对缓解汞胁迫下叶片伤害具有积极作用。

Physiological and biochemical indexes of detached leaves of Pseudosasa japonica which treated with different doses of Hg^2＋ and certain doses of La^3＋ were determined in order to study regulating effects of La^3＋ on physiological response of bamboo leaves and the relationship between La^3＋ and polyamine metabolism under Hg^2＋ stress. The results showed that the accession of cell membrane permeability and the descent of chlorophyll and protein content were inhibited obviously in the presence of 0.25 mg· L^-1 La（ NO3 ）3 under 10 mg· L^-1 mercury bichloride stress, and the damage of leaves was relieved noticeably. Under 50 mg· L^- 1 mercury bichloride stress, La^3＋ had no significant influence on relieving the damage of leaves. While Under 200 mg·L^- 1 mercury bichloride stress, synergistic effect of La^3＋ and Hg^2＋ appeared, La^3＋ even aggravated the damage of leaves. La^3＋ could also increase SOD activity and inhibit the elevation of POD activity,keep stabilizing of protective enzymes under 10 mg· L^-1 mercury bichloride stress. Alleviative effect of La^3＋ on mercury toxicity of P. japonica leaves was likely related with polyamine metabolism. La^3＋ treatment could promote noticeably endogenous putrescine （Put）, spermidine （Spd） and spermine （Spm） content of leaves under 10 mg· L^-1 mercury bichloride stress, which coincided with alleviative effect of La^3＋ ,and presented obviously positive correlation with the change of SOD activity. The study suggested that increasing of endogenous polyamine content was likely a pattern of alleviative effect of La^3＋ on mercury toxicity, and polyamines exerted positive effects on reducing injury of leaves under Hg^2＋ stress.