Cadmium Hyperaccumulator Potential of the Edible Cactus Nopalea cochenillifera

抄録

　In this study, we evaluated the impact of cadmium (Cd) supplementation on the growth of the edible cactus Nopalea cochenillifera (L.) Salm-Dyck and investigated its Cd accumulation capability by exposing hydroponically grown cladodes to 0, 1, or 15 ppm Cd for 10 weeks. The fresh weights of the daughter and mother cladodes in the 15 ppm Cd treatment were about 59.8% and 82.3% of those of 0 ppm Cd treatment (control). Cd concentration of daughter cladodes in 1 and 15 ppm Cd treatment were approximately 19 times and 65 times as high as control, and Cd concentration in all plant tissues surpassed the threshold levels of other known Cd hyperaccumulator plants. We also found that the Cd concentration was significantly higher outside than inside the vascular tissue under both the 1 and 15 ppm treatments by about 28 times and 45 times each, indicating that Cd transported from the roots accumulated outside the vascular system. These results suggest that N. cochenillifera has a high Cd tolerance and can store Cd inside plant tissues. In addition to its current role as healthy food and fodder, we believe that this cactus can be a promising candidate for Cd phytoremediation in arid regions.