Structure and diversity of 13S globulin zero-repeat subunit, the trypsin-resistant storage protein of common buckwheat ( M.) seeds.

The zero-repeat subunit of 13S globulin, which lacks tandem repeat inserts, is trypsin-resistant and suggested to show higher allergenicity than the other subunits in common buckwheat ( Moench). To evaluate allelic variations and find novel alleles, the diversity of the zero-repeat genes was examined for two Japanese elite cultivars and 15 Pakistani landraces. The results demonstrated that two new alleles and , plus three additional new alleles , , and , were identified besides the already-known , , and alleles. In the Pakistani landraces, was the most dominant allele (0.60-0.88 of allele frequency) in all except one landrace, where was the most dominant allele (0.50 of allele frequency). Similar to , the alleles and had extra ~200 bp MITE-like sequences around the stop codon. Secondary structure predictions of a sense strand demonstrated that the extra ~200 bp sequences of , , and can form rigid hairpin structures with free energies of -78.95, -67.06, and -29.90 kcal/mol, respectively. These structures may affect proper transcription and/or translation. In the homozygous line, no transcript of a zero-repeat gene was detected, suggesting the material would be useful for developing hypoallergenic buckwheat.