Identification of TaqW-6AS, a novel gene controlling WE-AX content in wheat grain.

key messageA novel gene, TaqW-6AS was discovered on chromosome 6AS which encodes a Class III heme peroxidase influencing WE-AX content in wheat grain. Water-extractable arabinoxylan (WE-AX), a key soluble dietary fiber component, provides various significant health benefits and exhibits notable functional properties. In this study, we detected QTLs for WE-AX content in two populations: a natural population of 163 varieties (ZZ population) genotyped with the Axiom wheat 90 K single nucleotide polymorphism (SNP) array, and a recombinant inbred line (RIL) population with 175 lines derived from a cross between Avocet and Huites (AH population) genotyped with diversity array technology (DArT). QWE-AX.haust-6A, a major-effect and stable co-localized locus associated with WE-AX content was detected by GWAS and linkage analysis which was on the short arm of chromosome 6A with the physical interval 1.09 Mb from 14.61 to 15.70 Mb in five environments. In the candidate region of QWE-AX.haust-6A, a gene temporarily named TaqW-6AS was cloned, which encodes a Class III heme peroxidase. TaqW-6AS protein was localized in the ER-Golgi secretory pathway. Furthermore, three functional markers (kasp-qw6A-1, kasp-qw6A-4, and kasp-qw6A-6) and two favorable haplotypes (Hap4 and Hap5) of TaqW-6AS were deployed effectively in marker-assisted selection (MAS) for biofortification breeding.