Barley chymotrypsin inhibitor-2 (CI-2) was considered to be a promising candidate for enhancing the nutritional value of other cereals by increasing its concentration as it is rich in lysine than any other storage protein. Also, it was proposed that CI-2 might play an important role in the inhibition of proteolytic enzymes from pests or pathogens as CI-2 can strongly inhibit chymotrypsin and subtilisin. In this study, a total of 93 CI-2 gene sequences were isolated from wild and cultivated barley. 48 SNPs and 4 indels were detected across the entire sequences. The frequency of SNPs in the non-coding region (1 out of 9 bases) was slightly higher than that in the coding region (1 out of 10.7 bases). In all, 33.3% of the candidate cSNPs resulted in amino acid changes. As a total, the 24 cSNPs resulted in 15 amino acid changes. Ten distinguishable haplotypes were detected, among which 3 haplotypes were shared in the most barley accessions, whereas the rest of the haplotypes appeared at a lower frequency. In addition, three haplotypes (haplotype 4, 8, and 9) were unique for single accessions. These results suggested that low diversity at the CI-2 locus was detected among the cultivated and wild barley.
The hina gene encodes a HINA protein in seeds of barley (Hordeum vulgare), which was known to affect the grainhardness. 171 hina gene sequences from Tibetan wild barley accessions and worldwide were characterized. Across 1 452nucleotides of 171 hina genes, 152 SNPs were detected, giving an average frequency of one SNP per 9.5 bases. There were93 singleton variable sites (the nucleotide polymorphism only observed in a single accession), 59 polymorphic sites (thepolymorphisms found in two or more accessions) and 8 indels. A total of 18 haplotypes were defined, and most of thebarley accessions shared one gene haplotype. H. spontaneum had a wider haplotype distribution. Through the analysisof median-joining network of the 18 haplotypes, 4 haplotype groups were found, which were testified by neighbor-joiningtree based on the complete sequence alignment. Extremely low level of hina gene diversity was observed in Tibetan wildbarley accessions, indicating that Tibet is unlikely a center of origin for cultivated barley.
YANG Shi-dongWEI Yu-mingQI Peng-feiZHENG You-liang
