The effects of ABA on channel-mediated K+ transport across higher plant roots

The transport and accumulation of K+ in higher plant roots is regulated by ABA, Molecular and electrophysiological techniques have identified a number of discrete transporters which are involved in the translocation of K+ fro m the soil solution to the shoots of higher plants. Furthermore, recent rep orts have shown that ABA regulates K+ channel activity in maize and Arabido psis roots which suggests that ABA regulation of K+ transport in roots is, at least in part, ion channel-mediated. The signalling processes which unde rlie the ABA regulation of K+ channels have been investigated. The effects of ABA on the membrane potential of intact maize root cells were also studi ed. It was found that ABA regulated the membrane potential of root cells an d that this regulation is consistent with the hypothesis that ABA-induced K + accumulation in roots is mediated by K+ channels.