The Tibetan hulless barley (Hordeum vulgare L. var. nudum), also called "Qingke" in Chinese and "Ne" in Tibetan, is the staple food for Tibetans and an important livestock feed in the Tibetan Plateau. The diploid nature and adaptation to diverse environments of the highland give it unique resources for genetic research and crop improvement. Here we produced a 3.89-Gb draft assembly of Tibetan hulless barley with 36,151 predicted protein-coding genes. Comparative analyses revealed the divergence times and synteny between barley and other representative Poaceae genomes. The expansion of the gene family related to stress responses was found in Tibetan hulless barley. Resequencing of 10 barley accessions uncovered high levels of genetic variation in Tibetan wild barley and genetic divergence between Tibetan and non-Tibetan barley genomes. Selective sweep analyses demonstrate adaptive correlations of genes under selection with extensive environmental variables. Our results not only construct a genomic framework for crop improvement but also provide evolutionary insights of highland adaptation of Tibetan hulless barley.Tibetan hulless barley | Triticeae evolution | genetic diversity | adaptation | selective sweep

Bacteria strains with strong virulence were isolated from pond-cultured tilapia in China. They were identified as Streptococcus agalactiae by biochemical assays, and confirmed by 16S ribosomal RNA (rRNA) and group B Streptococcus (GBS)-specific gene cfb analyses. Multiplex polymerase chain reaction (PCR) assay of the alpha C protein (ACP) gene and capsular polysaccharide antigen (cps) gene was employed to identify their molecular serotype (MS). Amplification of the ACP gene produced a 400-bp C alpha protein gene (bca) fragment, suggesting that these isolates belong to MS Ia, Ib or II; amplification of cps produced a 790-bp amplicon, indicating that they belong to MS Ia/III-3. An additional PCR based on nucleotide difference in the cps H-I region of MS Ia and III further suggested that the isolates belong to serotype MS Ia. Moreover, multi-locus sequence typing (MLST) indicated that these strains were of sequence type 7 (ST-7). These results showed that isolates from different regions of China shared the same MS and ST. However, none of the isolated ST-7 GBS corresponded to the capsular serotype, suggesting that these fish GBS possessed specific molecular characteristics not present in human or other animals. Data from this study will facilitate the understanding of epidemiology and nosogenesis of tilapia GBS and the establishment of effective disease prevention methods.

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