Aluminum tolerance genes are conserved between monocots and dicots

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Abstract
Acid soils are widespread throughout the world, being particularly prevalent in tropical and subtropical countries where food production is a major concern. The low pH of these soils solubilizes ionic forms of aluminum (Al) into the soil solution, and these Al species are toxic to plants, dramatically inhibiting root growth and function, which in turn results in severe crop-yield losses. The severity of this Al toxicity constraint to crop production was placed into perspective by da Silva (1), who described the early breeding efforts aimed at developing wheat cultivars adapted to soil acidity in areas of southern Brazil. Accordingly, in the early 1900s, these acid, Al-toxic soils imposed such a dramatic selection pressure that tolerant varieties yielding only ≈800–1,000 kg per hectare were considered satisfactory, whereas completely susceptible germplasm died before giving any yield. Fortunately, breeding for Al tolerance not only in wheat but also in several other crops has been extremely successful in expanding agriculture onto large areas of acid soils throughout the world, greatly contributing to food security worldwide, particularly in the poorest regions of the globe. One of the major Al tolerance genes that has played a vital role in this success is the focus of the work by Hoekenga et al. (2) in a recent issue of PNAS. By investigating Al tolerance in the model species Arabidopsis thaliana, the authors have made a significant contribution to the understanding of some important evolutionary aspects of plant Al tolerance, which can be used to foster a new molecular perspective for Al tolerance breeding in the grasses. Al tolerance in the tolerant wheat cultivar BH1146 is conditioned by a single major locus that controls nearly 85% of the phenotypic variation in a cross with the Al-sensitive cultivar Anahuac; this locus, designated Alt BH , was genetically mapped to …