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Phytochelatin synthesis in response to elevated CO₂ under cadmium stress in Lolium perenne L.

Jia, Yan, Ju, Xuehai, Liao, Shangqiang, Song, Zhengguo, Li, Zhongyang
Journal of plant physiology 2011 v.168 no.15 pp. 1723-1728
Lolium perenne, biomass, cadmium, carbon dioxide, coping strategies, culture media, exposure duration, heavy metals, hydroponics, metabolism, molecular weight, phytochelatins, roots, shoots, soil pollution
The increasing atmospheric CO₂ and heavy metal contamination in soil are two of the major environmental problems. Knowledge of the Cd stress coping mechanisms is needed to understand the regulation of the plants’ metabolism under the increasing atmospheric CO₂ levels. Lolium perenne L. was grown hydroponically under two concentrations of atmospheric CO₂ (360 and 1000μLL⁻¹) and six concentrations of cadmium (0–160μmolL⁻¹) to investigate Cd uptake, Cd transportation, and variations in phytochelatin (PC) concentration. Cd concentrations in roots and shoots were decreased, but transport index (Ti) was increased under elevated CO₂ compared to ambient CO₂. Regardless of CO₂ concentrations, Cd and PC concentrations, especially the concentrations of high molecular weight PCs (PC₄, PC₅, PC₆) were higher with increasing Cd concentration in growth media and longer Cd exposure time. Under the elevated CO₂, more high molecular weight PCs (PC₄, PC₅, PC₆) in shoots and roots were synthesized compared to ambient CO₂, with higher SH:Cd ratio in roots as well. These results indicate that under elevated CO₂, L. perenne may be better protected against Cd stress with higher biomass, lower Cd concentration and better detoxification by phytochelatins.