Survey of vitamin B6 and identification of genetic loci in wheat: a better understanding for breeding VB6-rich cultivars.

key messageIdentification and provision of genetic loci, candidate genes, critical germplasms, and theoretical evidence for breeding VB6-rich wheat cultivars. As a key functional component in daily diets, vitamin B6 (VB6) is essential for human metabolism. The consumption of VB6-rich wheat is an effective way to cope with human VB6 deficiency. We employed high-performance liquid chromatography to measure the wheat grain VB6 content of 262 accessions from a Chinese wheat mini-core collection grown in three different environments. The effects of the accession type and eleven agronomic traits on the VB6 content were analysed, and the QTLs associated with VB6 were mapped. The average total content of VB6 was 228.7 μg/100 g, and six accessions contained high contents of VB6 (> 320 μg/100 g). The effects on the VB6 content ranked as follows: genotype > genotype × environment > environment. The concentrations of VB6 did not significantly differ among accession types, between spring and winter varieties, or between red and white grains. The pyridoxine of VB6 was positively correlated with grain length but negatively correlated with plant height. Total VB6 was positively correlated with heading date, maturity date, grain length, and lutein content but negatively correlated with plant height. None of these correlations are believed to impose serious constraints on the breeding of VB6-rich wheat. Genome-wide association analysis revealed 12 stable QTLs associated with VB6, some of which showed cumulative effects. QPL.3A was verified in one population of doubled haploid lines. Transcriptomic analysis revealed four candidate genes for VB6 biosynthesis. This study provides genetic resources and theoretical evidence that is potentially useful for the breeding of VB6-rich wheat cultivars.