Genotyping the High Protein Content Gene NAM-B1 in Wheat (Triticum aestivum L.) and the Development of a KASP Marker to Identify a Functional Haplotype

Protein content is one of the main factors determining the end-use quality of wheat. NO APICAL MERISTEM-B1 (NAM-B1) is a major gene regulating wheat grain protein content. The present study aimed to identify new genetic resources using the wild-type NAM-B1 allele to breed high-protein-content wheat cultivars. We genotyped the HIGH GRAIN PROTEIN CONTENT-B1 (GPC-B1) locus and NAM-B1 allele in 165 wheat cultivars. A kompetitive allele-specific polymerase chain reaction (KASP) marker was designed for functional NAM-B1 allele screening. The results revealed that 41 out of 165 cultivars carried the GPC-B1 locus. Among the 41 GPC-B1-carrying cultivars, the wild-type NAM-B1 allele was identified in only 3 cultivars, none of which were Korean. The remaining 38 cultivars showed a 1-bp insertion in NAM-B1, resulting in a stop codon in the middle of the gene, rendering it nonfunctional. Overall, this study reveals that the utilization of the three selected cultivars possessing the wild-type NAM-B1 gene, in conjunction with the developed KASP assay, could increase the protein content in Korean wheat cultivars.