龙须菜对重金属汞胁迫的生理响应

摘要

The physiological responses of Gracilaria lemaneiformis exposed to various Hg2 + concentrations of 0, 0.02, 0.04, 0.10, 0.20 and 0.40 mg·L-1 were studied. The results showed that relative growth rate (RGR) of G. lemaneiformis was significantly reduced by 0.02 mg·L-1 Hg2+ or more compared to the control. The algae even exhibited negative RGR at Hg2+ concentrations of 0.20 and 0.40 mg·L-1. With the increasing concentrations of Hg2+, the optimal quantum yield (Fv / Fm) , the maximum net photosynthetic rate (Pmax) and the apparent photosynthetic efficiency (a) were markedly depressed. The contents of chlorophyll a, carotenoid and phycobiliprotein were increased with the lower concentrations of Hg2+, but they were significantly decreased at Hg2* concentrations of 0.10 mg·L-1 or more. Our results indicated that Hg2+ appeared to be a highly toxic heavy metal to G. lemaneiformis. G. lemaneiformis possessed a poor tolerance to mercury stress, with the physiological activity being markedly affected when the Hg2+ concentration was 0.02 mg·L-1 or more.%研究了大型海藻龙须菜(Gracilaria lemaneiformis)对不同浓度重金属汞(0、0.02、0.04、0.10、0.20和0.40 mg/L)胁迫的生理响应.结果表明:当Hg2+浓度≥0.02 mg/L时,龙须菜藻体的相对生长速率显著下降,并且当Hg2+浓度达到0.20和0.40 mg/L时,龙须菜出现负增长.随着Hg2+浓度的升高,龙须菜藻体的最大光化学量子产量、最大净光合速率和表观光合效率逐渐下降,叶绿素a、类胡萝卜素和藻胆蛋白含量则呈先升高后下降的趋势,且当Hg2+浓度≥0.10 mg/L时,叶绿素a、类胡萝卜素和藻胆蛋白含量显著下降.说明龙须菜在受Hg2+胁迫的环境中耐受性较差,且Hg2+对龙须菜的毒害作用较大,当Hg2+浓度≥0.02 mg/L时,龙须菜藻体的生理活动就会受到显著抑制.