A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum

Abstract

Crop yields are significantly reduced by aluminum toxicity on highly acidic soils, which comprise up to 50% of the world's arable land. Candidate aluminum tolerance proteins include organic acid efflux transporters, with the organic acids forming non-toxic complexes with rhizosphere aluminum. In this study, we used positional cloning to identify the gene encoding a member of the multidrug and toxic compound extrusion (MATE) family, an aluminum-activated citrate transporter, as responsible for the major sorghum (Sorghum bicolor) aluminum tolerance locus, Alt(SB). Polymorphisms in regulatory regions of Alt(SB) are likely to contribute to large allelic effects, acting to increase Alt(SB) expression in the root apex of tolerant genotypes. Furthermore, aluminum-inducible Alt(SB) expression is associated with induction of aluminum tolerance via enhanced root citrate exudation. These findings will allow us to identify superior Alt(SB) haplotypes that can be incorporated via molecular breeding and biotechnology into acid soil breeding programs, thus helping to increase crop yields in developing countries where acidic soils predominate.

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…In a genome-wide association study targeting adaptation to low P in sorghum (Leiser et al, 2014b), the most significant association with grain yield was found for an SNP at position 71.1 Mb on chromosome 3 (71178053), only 35.7 kb from the aluminum tolerance gene Sorghum bicolor multidrug and toxic compound extrusion (SbMATE), which underlies the aluminum tolerance locus Aluminum tolerance Sorghum bicolor (Alt SB ; Magalhaes et al, 2007). As SNPs associated with grain yield were also found within Alt SB and SbMATE, this suggests a possible pleiotropic effect of SbMATE in providing tolerance to aluminum toxicity and to low-P conditions (Leiser et al, 2014b).…”

Knockout of a Bacterial-Type ATP-Binding Cassette Transporter Gene, AtSTAR1, Results in Increased Aluminum Sensitivity in Arabidopsis

“…This mechanism has been observed in a wide variety of plant species, including both dicots and monocots such as wheat (Triticum aestivum), barley (Hordeum vulgare), Arabidopsis, and Cassia tora (Delhaize et al, 1993;Ma et al, 1997;Hoekenga et al, 2003;Zhao et al, 2003). Genes responsible for the Alinduced secretion of malate in wheat (ALMT1; Sasaki et al, 2004), and citrate in barley (HvAACT1; Furukawa et al, 2007) and sorghum (SbMATE;Magalhaes et al, 2007) have been identified. Recently, progress in identification of other Al-tolerance genes has also been made.…”

Stress Response Versus Stress Tolerance: A Transcriptome Analysis of Two Rice Lines Contrasting in Tolerance to Phosphorus Deficiency

“…In any case, increased synthesis of LMWOAs is not necessarily indicative of a higher LMWOA exudation since the limiting step is not the plantinternal concentration of LMWOAs (synthesis) but their rate of release (Delhaize et al 2001). This release is mediated by specific efflux transporters, and their level of activity was shown to be directly linked to malate or citratemediated tolerance to excess aluminum (Delhaize et al 2004;Magalhaes et al 2007). However, putative efflux transporters were not among the root-specific genes differentially expressed between genotypes, corroborating earlier results that neither genotype exuded citrate or malate at high enough concentrations to have a significant effect on P solubilization (Wissuwa 2005).…”