Mardi 8 novembre 2005

Anne-Alienor Véry (B&PMP Equipe Canaux Ioniques)

K+ transport in plants – Functional diversity among HKT transporters and Shaker channels

Potassium, as a macronutrient, plays a number of important roles in plant growth and development. Over the past decade, molecular approaches have led to the identification of several tens of genes (putatively) coding for K+ transport systems in plants. Among them, Shaker channels are already quite well characterised. Detailed functional data are available for almost all Arabidopsis members and also for several members in other plant species, which already gives a quite good idea of the main functional types present in the family and the role they play or might play in the plant. Other families of plant K+ channels and transporters have been less extensively studied. Among them, the family of HKT transporters has been hypothesised to be involved in K+ transport, but the actual role of these systems in K+ transport is still obscure. In particular, the unique member of this family in Arabidopsis is not permeable to K+. The identification of 9 HKT genes in rice gives the opportunity to increase our knowledge on the different functional types present within this family The current knowledge on functional diversity within these two families of plant K+ transport systems (Shakers and HKT transporters) will be illustrated with examples from Arabidopsis, barley, maize and rice, and remaining interrogations on the roles of these systems in the plant will be evoked.