Genetic identification and characterization of two novel loci for grain arsenic concentration in tetraploid wheat at various field environments

Abstract

Aims

Arsenic (As) is a highly toxic metalloid that can accumulate in wheat, posing significant human health risks. However, the genetic basis underlying As accumulation in wheat grains remains largely unexplored.

Methods

This study utilized a recombinant inbred line (RIL) population derived from an endemic tetraploid wheat variety and a wild emmer accession. Phenotypic data were collected from three field environments and a pot experiment with three As levels.

Results

Seven quantitative trait loci (QTL) associated with grain As concentration (GrAsc) were identified. Among these, two major QTL—QGrAsc.sau-AM-1A and QGrAsc.sau-AM-4A— were located on chromosomes 1A and 4A, respectively, and were detected in over four environments. These loci, which explained 7.96% to 12.51% and 10.20% to 21.45% of phenotypic variance, respectively, and were successfully validated using Kompetitive Allele-Specific PCR (KASP) markers in a natural population. Additionally, four wheat varieties with low As concentrations were screened using KASP markers. Comparisons with previous studies suggest that these two major QTL are likely novel. Furthermore, the effects of QGrAsc.sau-AM-1A and QGrAsc.sau-AM-4A on GrAsc were analyzed. Candidate genes related to As uptake and transport were predicted to be associated with these loci. Correlation analysis between GrAsc and nine agronomic traits revealed a significant negative correlation with thousand kernel weight (TKW). Additionally, QGrAsc.sau-AM-1A was found to significantly increase spikelet number per spike, while QGrAsc.sau-AM-4A was associated with increased spike density. Overall, these results suggest that QGrAsc.sau-AM-1A and QGrAsc.sau-AM-4A are promising loci for further fine mapping and molecular breeding aimed at reducing As accumulation in wheat.

Conclusions

Two novel, major QTL—QGrAsc.sau-AM-1A and QGrAsc.sau-AM-4A— were identified for grain arsenic concentration. Their effects were validated in a natural wheat population, offering the potential for marker-assisted selection (MAS) and molecular breeding.