Newly cloned wheat gene TaqW-6BL boosts grain fiber content

Researchers have cloned a wheat gene called TaqW-6BL that positively regulates the content of water-extractable arabinoxylans (WE-AX), a major group of dietary fiber components in wheat grains that also influences the crop’s end-use and nutritional quality.

The gene was isolated from the parental varieties of a recombinant inbred line population. Within the gene, the team detected a missense mutation at position +296 bp, a T/C change, that causes a single amino acid substitution, replacing methionine with threonine.

Functional tests showed the gene’s effect clearly. Overexpression of TaqW-6BL increased grain WE-AX content by 30.80%, thousand kernel weight by 14.59%, and mean grain perimeter by 14.53%. Conversely, CRISPR/Cas9-mediated knockout of the gene led to significant decreases in all three traits.

Cytological observations helped explain these changes. In the overexpression lines, the aleurone layer partially proliferated into two layers, while knockout lines showed disordered cell arrangement and abnormal morphology, linking the gene’s activity to grain structural development.

Subcellular localization analysis confirmed that the TaqW-6BL protein localizes in the endoplasmic reticulum.

The researchers also compared two natural haplotypes of the gene, TaqW-6BLAvocet and TaqW-6BLChilero. At 14 and 21 days after flowering, the favorable haplotype TaqW-6BLAvocet showed significantly higher relative expression levels and WE-AX content than the unfavorable haplotype TaqW-6BLChilero, with P < 0.01.

To make the finding usable in breeding, the team developed a functional cleaved amplified polymorphic sequence (CAPS) marker, named CAPS-6B-296, which distinguishes the two haplotypes.

Surveying 160 wheat varieties with this marker, the researchers found that varieties carrying the favorable haplotype TaqW-6BLAvocet accounted for 68% of the set.

The authors conclude that their findings provide a valuable gene and a reliable functional marker for nutritional quality breeding in wheat, offering breeders a molecular tool to select varieties with higher grain fiber content.

Subject of Research: Cloning and functional characterization of the wheat gene TaqW-6BL, which regulates grain water-extractable arabinoxylan content

Article Title: TaqW-6BL, a novel gene positively regulates grain WE-AX content in wheat

Article References: Li, Q., Zeng, Z., Zhao, Y., Bi, J., Yan, Q., & Wang, C. (2026). TaqW-6BL, a novel gene positively regulates grain WE-AX content in wheat. Theoretical and Applied Genetics, 139(11), Article 314. https://doi.org/10.1007/s00122-026-05417-0

Image Credits: AI Generated

DOI: 10.1007/s00122-026-05417-0

Keywords: wheat, TaqW-6BL, water-extractable arabinoxylans, dietary fiber, CRISPR/Cas9, grain quality, CAPS marker, haplotype, aleurone layer, nutritional quality breeding, novel, gene