Researchers have identified genomic regions and genetic markers associated with dietary fiber traits in spelt wheat, providing potential tools for breeding wheat varieties with improved nutritional quality.
Spelt wheat is a genetically diverse hexaploid wheat species adapted to low-input agricultural systems. However, the genetic basis of its dietary fiber composition has remained poorly understood.
The study evaluated 255 genotypes, including spelt, bread wheat and wild hexaploid accessions. Researchers used a 25K single nucleotide polymorphism (SNP) array to genotype the material and evaluated fiber traits over two consecutive years.
The researchers conducted genome-wide association studies while accounting for population structure. They also identified candidate genes within 1 megabase on either side of significant SNPs based on functional annotations.
Significant differences were observed between spelt and bread wheat. Spelt consistently had lower levels of soluble fiber components, including water-extractable pentosans, beta-glucan and fructans. Total pentosan content, however, was comparable between the groups.
The genome-wide association studies identified 24 significant marker-trait associations for total pentosan content, 10 for water-extractable pentosan, 17 for beta-glucan and 20 for fructan content. Major genomic regions associated with fiber-related traits were identified on chromosomes 1B, 2A, 2B, 5A, 5B, 5D, 6B and 7A.
Several stable SNP markers showed consistent phenotypic effects across both years and distinguished allele variants characteristic of spelt. One spelt-specific marker was associated with beta-glucan content, indicating potentially valuable genetic variation for improving grain quality.
Researchers also identified candidate genes involved in carbohydrate metabolism and cell wall biosynthesis near the associated genomic regions. These included genes encoding glycosyltransferases, cellulose synthase-like proteins and enzymes involved in fructan metabolism.
In addition, 16 diagnostic spelt-specific SNP markers reliably distinguished homogeneous spelt lines from bread wheat lines.
The findings provide new information about the genetic architecture of fiber-related quality traits in wheat and molecular resources that could support marker-assisted breeding and genetic identification of spelt germplasm.
Source: Frontiers in Plant Science, "Genome-wide association analysis of fiber-related traits and identification of diagnostic SNP markers differentiating spelt wheat (Triticum spelta L.) from bread wheat"