Figure 1.

Adaptations to respond to variable copper supply in plants. When copper is limiting, Chlamydmonas degrades plastocyanin (PC) and its function is replaced by cytochrome c₆ (CYC6). In contrast to this algal strategy, Arabidopsis switches from the use of Cu/Zn SoD to iron SoD in response to copper deficiency and this switch involves the function of miR398. The strategy of Physcomitrella patens is likely to be similar to that of Arabidopsis, although the involvement microRNA is presently unclear.