No abstract

SummaryThe Arabidopsis AtMTP family of genes encode proteins of the cation diffusion facilitator (CDF) family, with several members having roles in metal tolerances. Four of the 11 proteins in the family form a distinct cluster on a phylogenetic tree and are closely related to ShMTP8, a CDF identified in the tropical legume Stylosanthes hamata that is implicated in the transport of Mn 2+ into the vacuole as a tolerance mechanism. Of these four genes, AtMTP11 was the most highly expressed member of the Arabidopsis subgroup.

Soluble aluminium (Al 3+ ) is the major constraint to plant growth on acid soils. Plants have evolved mechanisms to tolerate Al 3+ and one type of mechanism relies on the efflux of organic anions that protect roots by chelating the Al 3+ . Al 3+ resistance genes of several species have now been isolated and found to encode membrane proteins that facilitate organic anion efflux from roots. These proteins belong to the Al 3+ -activated malate transporter (ALMT) and multi-drug and toxin extrusion (MATE) families. We review the roles of these proteins in Al 3+ resistance as well as their roles in other aspects of mineral nutrition.