Identification and molecular characterization of novel LMW-m and -s glutenin genes, and a chimeric -m/-i glutenin gene in 1A chromosome of three diploid Triticum species

Abstract

Low molecular weight glutenin subunits (LMWGs) are part of the gluten network that gives dough its viscoelastic properties. A-genome-containing diploid species related to modern polyploid wheat show great variability in these subunits. The current study characterized the variability of LMW-m and -s genes, being identified fifteen LMWGs genes in the three species evaluated, of which 14 were novel. Ten were pseudogenes, which are common in cereal prolamins. The rest of genes, with intact coding region, corresponded to the LMW-m genes and some single nucleotide polymorphisms and insertion/deletion events were detected, which could alter protein structure and affect dough quality. Two variants of the LMW-s genes were detected in cultivated einkorn and Triticum urartu, the former being novel. The LMW-m and -s genes were related to TuA3-391 and TuA3-400 genes, and to the Tu-460 gene, respectively, of T. urartu. Screening the sequences characterized for reactive epitopes of celiac disease revealed that LMW-m could be less toxic than other subunits for celiac patients. One novel chimeric gene with features from LMW-m and LMW-i genes was detected in T. urartu, and it produces a novel mature protein that may have a distinguishing effect on dough quality. Novel insights into the evolution of LMWGs genes are also reported. These species are a potential source of novel LMWGs variants.