Genome-wide association analysis for arabinoxylan content in common wheat (T. Aestivum L.) flour

Arabinoxylans (AX) are the major components of dietary fibers (DF) in wheat grain and their consumption has been associated with multiple health benefits. Selection of wheat varieties with higher AX content could be an efficient approach to improve the daily consumption of DF. Here, the genetic variability of the total (TOT-AX) and water-extractable arabinoxylans (WE-AX) present in refined flour was investigated using a panel of 175 common wheat lines. Wide variation in both TOT-AX (10.79-16.54 mg/g) and WE-AX (3.19-7.63 mg/g) was found across the panel, with the genotype explaining a greater percentage of AX variation compared to the environment. Genomic regions associated with AX were investigated through genome-wide association study (GWAS) which revealed the association of five SNPs on chromosomes 1BL and 5BS with TOT-AX, and of 13 SNPs on chromosomes 1BL, 2BS, 6BS, 7A and 7BL with WE-AX. Markers on chromosome 1BL were coincident for both the AX fractions and explained the greatest percentage of phenotypic variation (13.29-17.22% for TOT-AX; 11.56-19.37% for WE-AX). In silico analysis of the genomic region delimited by the most significant 1BL markers (similar to 8 Mb) identified a predicted gene encoding for a glycosyl transferase (GT) of the GT61 family which is likely a candidate gene associated with the observed AX variation. Lastly, the four most significant 1BL GBS markers identified through the GWAS analysis were translated into Kompetitive allele specific PCR (KASP) markers. Results of this study constitute an important contribution for the improvement of grain DF in wheat breeding programs.