Anion channels in higher plants: functional characterization, molecular structure and physiological role

Anion channels are well documented in various tissues, cell types and membr anes of algae and higher plants, and current evidence supports their centra l role in cell signaling, osmoregulation, plant nutrition and metabolism. I t is the aim of this review to illustrate through a few selected examples t he variety of anion channels operating in plant cells and some of their reg ulation properties and unique physiological functions. In contrast, informa tion on the molecular structure of plant anion channels has only recently s tarted to emerge. Only a few genes coding for putative plant anion channels from the large chloride channel (CLC) family have been isolated, and curre nt molecular data on these plant CLCs are presented and discussed. A major challenge remains to identify the genes encoding the various anion channels described so far in plant cells. Future prospects along this line are brie fly outlined, as well as recent advances based on the use of knockout mutan ts in the model plant Arabidopsis thaliana to explore the physiological fun ctions of anion channels in planta. (C) 2000 Elsevier Science B.V. All righ ts reserved.