Role of Copper Binding, Absorption, and Translocation in Copper Tolerance ofAgrostis giganteaRoth

Abstract

The capacity of roots to accumulate and retain copper was examined in two clones of Agrostis gigantea which differ in their tolerance to excess copper. Root elongation growth in the non-tolerant clone was completely inhibited by 16 mmol m⁻³ Cu whereas 40 mmol m⁻³ was required for inhibition in the tolerant clone. The amount of readily exchangeable copper was greater in roots of the tolerant clone than in the non-tolerant clone. The higher capacity for binding copper did not prevent the entry of copper into the cells of intact or excised roots of the tolerant clone. Roots of both clones contained similar amounts of copper after removal of the readily exchangeable fraction. More copper was translocated to the shoots of the tolerant than the non-tolerant clone. The explanation of copper tolerance in Agrostis gigantea must be sought in areas other than those of differences in gross copper absorption and retention by roots.