Effects of exogenous spermidine on subcellular distribution and chemical forms of cadmium in Typha latifolia L. under cadmium stress

摘要

The effects of foliar spraying with spermidine (Spd) on the subcellular distribution and chemicalnspeciation of Cd in Typha latifolia L. in hydroponic system were investigated. IncreasednCd concentration in the medium caused an increase of Cd concentration in all tissues and allnsubcellular fractions, with the highest Cd level occurring in roots, followed by rhizomes andnleaves and the greatest accumulation was in cell walls, soluble fraction and organelle containingnfractions ranked next, respectively. The greatest amount of Cd was found in the extractionnof 1 mol·L21 NaCl, followed by 2% HAC, deionized water, 80% ethanol, residues and the leastnin 0.6 mol·L21 HCl. The subcellular distribution and different chemical forms of Cd both decreasednafter Spd application and were more inhibited by 0.25 than 0.50 mmol·L21 Spd, especially in rootsnat 0.10 mmol·L21 Cd treatment. It could be suggested that the retention of Cd in roots, cell wallsnbinding with metal, metal ion compartmentation in vacuoles and Cd forms existing in undissolvednand integrated with pectates and protein play an important role in Cd detoxification and Spdncould enhance the tolerance of cattail to Cd stress.