镧对汞胁迫下豌豆幼苗光合能力的影响

Effect of La on Photosynthesis of Pisum sativum Seedlings under Hg Stress

以培养5d的豌豆(PisumsativumL )幼苗为实验材料,研究不同浓度La对10mg·L-1和50mg·L-1Hg胁迫下的生理效应。结果表明,适量的La能在一定程度上缓解Hg胁迫所导致的叶绿素、可溶性蛋白含量、光合速率、叶绿体Mg2+ ATPase、光合膜电子传递链活性及PSII活性的降低,减轻Hg胁迫对光合膜室温下吸收光谱和荧光光谱的影响;能有效增强或保护Hg胁迫下叶片细胞总抗氧化能力,降低细胞内Hg胁迫诱导超氧阴离子(O2-·)产生的速率和膜脂过氧化产物(MDA)的积累,延缓膜透性的增加。La对10mg·L-1Hg胁迫的缓解能力较强,而对50mg·L-1Hg的缓解效果较弱。最佳作用浓度为0 010mg·L-1。该浓度的La能有效减少细胞对Hg的吸收和积累,有效防护Hg胁迫对叶绿体光合能力的损伤。超过一定浓度范围的La则加剧Hg的毒害。

To study the physiological effect of La on photosynthesis under Hg stress,Pisum sativum L seedlings were cultivated for 5 days in solution containing different concentrations of Hg and La. The results show that La alleviates the reduction of chlorophyll and soluble protein content, increases the activity of whole electron transport chain, PSⅡ and Mg^(2+)-ATPase in chloroplast, protects the absorption spectrum and fluorescence emission spectrum at room temperature under Hg stress, thereby alleviates the hurt on photosynthesis. It also increases the total antioxicatability, deletes O_2^(-·) and MDA, reduces the relative membrane permeability. Besides, it lessens the absorbability and accumulation of Hg. La is more effective against 10 mg·L^(-1) Hg treatment than 50 mg·L^(-1) one and 0.010 mg·L^(-1) La is optimum concentration. However, when the concentration of La exceeds certain limit (≥0.030 mg·L^(-1)) ,it will aggravate the stress of high Hg concentration.