Back to Acid Soil Fields: The Citrate Transporter SbMATE Is a Major Asset for Sustainable Grain Yield for Sorghum Cultivated on Acid Soils

Abstract

Aluminum (Al) toxicity damages plant roots and limits crop production on acid soils, which comprise up to 50% of the world’s arable lands. A major Al tolerance locus on chromosome 3, AltSB, controls aluminum tolerance in sorghum [Sorghum bicolor (L.) Moench] via SbMATE, an Al-activated plasma membrane transporter that mediates Al exclusion from sensitive regions in the root apex. As is the case with other known Al tolerance genes, SbMATE was cloned based on studies conducted under controlled environmental conditions, in nutrient solution. Therefore, its impact on grain yield on acid soils remains undetermined. To determine the real world impact of SbMATE, multi-trait quantitative trait loci (QTL) mapping in hydroponics, and, in the field, revealed a large-effect QTL colocalized with the Al tolerance locus AltSB, where SbMATE lies, conferring a 0.6 ton ha–1 grain yield increase on acid soils. A second QTL for Al tolerance in hydroponics, where the positive allele was also donated by the Al tolerant parent, SC283, was found on chromosome 9, indicating the presence of distinct Al tolerance genes in the sorghum genome, or genes acting in the SbMATE pathway leading to Al-activated citrate release. There was no yield penalty for AltSB, consistent with the highly localized Al regulated SbMATE expression in the root tip, and Al-dependent transport activity. A female effect of 0.5 ton ha–1 independently demonstrated the effectiveness of AltSB in hybrids. Al tolerance conferred by AltSB is thus an indispensable asset for sorghum production and food security on acid soils, many of which are located in developing countries.

The genetic architecture of biomechanical traits in sorghum

“…A multitrait QTL analysis was performed for each trait with the BLUEs calculated for each individual experiment from each RIL population. A mixed‐model approach using GenStat 18.1 (VSN International) was used for the multitrait QTL mapping as described by several authors (Assanga et al., 2017; Bhakta et al., 2017; Boer et al., 2007; Carvalho et al., 2015; Malosetti, Ribaut, & van Eeuwijk, 2013; Malosetti, Ribaut, Vargas, Crossa, & Van Eeuwijk, 2008; Sukhwinder‐Singh et al., 2012). Unlike single‐trait QTL analysis, the multitrait QTL analysis permits the evaluation of pleiotropy and linkage of genes as causes of genetic relationship between traits (Sukhwinder‐Singh et al., 2012).…”

“…The final mixed‐effect model had the form responses = QTL + polygenic effects + errors. The percentage of genetic variance explained by a QTL was estimated from the drop of polygenic variance that occurred when the QTL was included in a model with only polygenic effects: responses = polygenic effects + errors (Carvalho et al., 2015).…”

Improving phosphorus use efficiency: a complex trait with emerging opportunities

“…Similarly, a gene ( SbMATE ) for Al 3+ tolerance of root growth in sorghum has been associated with improved Pi uptake efficiency in field trials (Leiser et al ., ; Carvalho et al ., ). SbMATE is a member of the Multidrug and Toxic Compound Extrusion (MATE) transporter family, and is responsible for citrate efflux from roots.…”

Repeat variants for the SbMATE transporter protect sorghum roots from aluminum toxicity by transcriptional interplay incisandtrans

“…Half the world's agricultural soils are highly acidic (3), which solubilizes Al 3+ into the soil solution, damaging plant roots and reducing yields. The Al-activated root citrate transporter SbMATE, which underlies Al tolerance via formation of nontoxic Al-citrate complexes in the rhizosphere (4), increased grain yield by 0.6 ton·ha −1 for sorghum grown on acidic soil (5). SbMATE SNPs were associated to sorghum grain yield production in West Africa (6), where sorghum is a staple food.…”