龙须菜对重金属铜胁迫的生理响应

研究了大型海藻龙须菜(Gracilaria lemaneiformis)对不同浓度重金属铜(0、25、50、100、250和500 μg·L^-1)胁迫的生理响应.结果表明:当Cu²⁺浓度≥50 μg·L^-1时，龙须菜藻体的相对生长速率显著下降，最大光化学量子产量、最大相对电子传递速率和相对电子传递效率呈相同的变化趋势.随着Cu²⁺浓度的升高，龙须菜藻体最大净光合速率和光饱和点显著降低，而光补偿点显著升高，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；当Cu²⁺浓度达到500 μg·L^-1时，叶绿素a、类胡萝卜素和藻胆蛋白含量显著下降.说明龙须菜在低浓度Cu²⁺胁迫下具有一定的抵抗能力，而当Cu²⁺浓度≥50 μg·L^-1时，会对藻体生理活动造成显著的抑制作用.

Physiological responses of Gracilaria lemaneiformis to copper stress.

Gracilaria lemaneiformis was exposed to 0, 25, 50, 100, 250 and 500 μ g·L-1 of Cu2+ to study its physiological responses to Cu2+ st ress. When the Cu2+ concentration was ≥50 μg·L-1, the relative gr owth rate (RGR) of G. lemaneiformis decreased significantly, and the optimal quantum yield (Fv/Fm), the maximum relative electron transfer rate (r ETRmax), and the relative electron transfer efficiency (α) exhibited th e same variation trend, compared with the control. With the increase of Cu2+  concentration, the maximum net photosynthetic rate (Pmax) and l ight saturation point (LSP) decreased significantly, light compensation poin t (LCP) had a significant increase, while chlorophyll a, carotenoid, and phy cobiliprotein contents decreased after an initial increase. When the Cu2+ concentration reached 500 μg·L-1, the chlorophyll a, carotenoid, and phy cobiliprotein contents decreased significantly. It was suggested that G. leman eiformis could tolerate low concentration Cu2+ stress, but its physiolog ical activities were inhibited markedly when exposed to ≥50 μg·L-1 of C u2+.