Chromosome-scale assembly of barley cv. 'Haruna Nijo' as a resource for barley genetics

Genomic traces of Japanese malting barley breeding in two modern high-quality cultivars, 'Sukai Golden' and 'Sachiho Golden'

Two modern high-quality Japanese malting barley cultivars, 'Sukai Golden' and 'Sachiho Golden', were subjected to RNA-sequencing of transcripts extracted from 20-day-old immature seeds. Despite their close relation, 2,419 Sukai Golden-specific and 3,058 Sachiho Golden-specific SNPs were detected in comparison to the genome sequences of two reference cultivars: 'Morex' and 'Haruna Nijo'. Two single nucleotide polymorphism (SNP) clusters respectively showing the incorporation of (1) the barley yellow mosaic virus (BaYMV) resistance gene rym5 from six-row non-malting Chinese landrace Mokusekko 3 on the long arm of 3H, and (2) the anthocyanin-less ant2 gene from a two-row Dutch cultivar on the long arm of 2H were detected specifically in 'Sukai Golden'. Using 221 recombinant inbred lines of a cross between 'Ishukushirazu' and 'Nishinochikara', another BaYMV resistance rym3 gene derived from six-row non-malting Japanese cultivar 'Haganemugi' was mapped to a 0.4-cM interval on the proximal region of 5H. Haplotype analysis of progenitor accessions of the two modern malting cultivars revealed that rym3 of 'Haganemugi' was independently introduced into 'Sukai Golden' and 'Sachiho Golden'. Residual chromosome 5H segments of 'Haganemugi' surrounding rym3 were larger in 'Sukai Golden'. Available results suggest possibilities for malting quality improvement by minimizing residual segments surrounding rym3.

Towards the Investigation of the Adaptive Divergence in a Species of Exceptional Ecological Plasticity: Chromosome-Scale Genome Assembly of Chouardia litardierei (Hyacinthaceae)

One of the central goals of evolutionary biology is to understand the genomic basis of adaptive divergence. Different aspects of evolutionary processes should be studied through genome-wide approaches, therefore maximizing the investigated genomic space. However, in-depth genome-scale analyses often are restricted to a model or economically important species and their closely related wild congeners with available reference genomes. Here, we present the high-quality chromosome-level genome assembly of Chouardia litardierei, a plant species with exceptional ecological plasticity. By combining PacBio and Hi-C sequencing technologies, we generated a 3.7 Gbp genome with a scaffold N50 size of 210 Mbp. Over 80% of the genome comprised repetitive elements, among which the LTR retrotransposons prevailed. Approximately 86% of the 27,257 predicted genes were functionally annotated using public databases. For the comparative analysis of different ecotypes' genomes, the whole-genome sequencing of two individuals, each from a distinct ecotype, was performed. The detected above-average SNP density within coding regions suggests increased adaptive divergence-related mutation rates, therefore confirming the assumed divergence processes within the group. The constructed genome presents an invaluable resource for future research activities oriented toward the investigation of the genetics underlying the adaptive divergence that is likely unfolding among the studied species' ecotypes.

BGFD: an integrated multi-omics database of barley gene families

BACKGROUND

A gene family comprises a group of genes with similar functional domains that play various roles in plant growth, development, and responses to environmental stimuli. Barley (Hordeum vulgare L.) is the fourth most cultivated cereal crop worldwide, and it is an important model species for genetic studies. Systematic identification and annotation of gene families are key for studies of molecular function and evolutionary history.

RESULTS

We constructed a multi-omics database containing 5593 genes of 77 gene families called the Barley Gene Family Database (BGFD: http://barleygfdb.com ). BGFD is a free, user-friendly, and web-accessible platform that provides data on barley family genes. BGFD provides intuitive visual displays to facilitate studies of the physicochemical properties, gene structure, phylogenetic relationships, and motif organization of genes. Massive multi-omics datasets have been acquired and processed to generate an atlas of expression pattern profiles and genetic variation in BGFD. The platform offers several practical toolkits to conduct searches, browse, and employ BLAST functions, and the data are downloadable.

CONCLUSIONS

BGFD will aid research on the domestication and adaptive evolution of barley; it will also facilitate the screening of candidate genes and exploration of important agronomic traits in barley.