Siberian wildrye (Elymus sibiricus L.) is a perennial, self-fertilizing grass that plays an important role in animal husbandry and environmental sustenance. However, the transcriptomic and genomic information on this species is very limited, which hinders genetic and breeding studies. In the present study, 76,686,804 clean reads were generated from 11 different tissue samples of E. sibiricus by Illumina paired-end sequencing, and the reads were deposited into the NCBI SRA database (SRX574376). A total of 8,769 EST-SSRs were identified from 94,458 unigene sequences, which were obtained by de novo assembly. Moreover, 1,078 primer pairs were successfully designed, and 500 pairs were randomly selected to assess polymorphisms in 15 E. sibiricus accessions. A total of 112 primer pairs were polymorphic, and the polymorphism information content (PIC) values ranged from 0.39 to 0.81, indicating a high level of informativeness. Furthermore, these 112 polymorphic primer pairs were used to evaluate the transferability to 13 other related species, and 55 EST-SSR markers were found to be polymorphic among these 13 Elymus species. This study collected the global sequence data for E. sibiricus, and the newly developed markers will prove valuable in facilitating genetic diversity in E. sibiricus and related Elymus species.

SummaryOrchardgrass (Dactylis glomerata L.) is an important forage grass for cultivating livestock worldwide. Here, we report an ~1.84‐Gb chromosome‐scale diploid genome assembly of orchardgrass, with a contig N50 of 0.93 Mb, a scaffold N50 of 6.08 Mb and a super‐scaffold N50 of 252.52 Mb, which is the first chromosome‐scale assembled genome of a cool‐season forage grass. The genome includes 40 088 protein‐coding genes, and 69% of the assembled sequences are transposable elements, with long terminal repeats (LTRs) being the most abundant. The LTRretrotransposons may have been activated and expanded in the grass genome in response to environmental changes during the Pleistocene between 0 and 1 million years ago. Phylogenetic analysis reveals that orchardgrass diverged after rice but before three Triticeae species, and evolutionarily conserved chromosomes were detected by analysing ancient chromosome rearrangements in these grass species. We also resequenced the whole genome of 76 orchardgrass accessions and found that germplasm from Northern Europe and East Asia clustered together, likely due to the exchange of plants along the ‘Silk Road’ or other ancient trade routes connecting the East and West. Last, a combined transcriptome, quantitative genetic and bulk segregant analysis provided insights into the genetic network regulating flowering time in orchardgrass and revealed four main candidate genes controlling this trait. This chromosome‐scale genome and the online database of orchardgrass developed here will facilitate the discovery of genes controlling agronomically important traits, stimulate genetic improvement of and functional genetic research on orchardgrass and provide comparative genetic resources for other forage grasses.

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The seed dispersion caused by pod shattering is a form of propagation used by many wild species. Loss of seeds from pod shattering is frequent in the common vetch (Vicia sativa L.), an important self-pollinating annual forage legume. However, pod shattering is one of the most important defects that limits the reproduction of the vetch in the field and the usage as a leguminous forage crop. To better understand the vetch pod shattering mechanism, we used high-throughput RNA sequencing to assess the global changes in the transcriptomes of the pod ventral sutures of shattering-susceptible and shattering-resistant vetch accessions screened from 541 vetch germplasms. A total of 1,285 significantly differentially expressed unigenes (DEGs) were detected, including 575 up-regulated unigenes and 710 down-regulated unigenes. Analyses of Gene Ontology and KEGG metabolic enrichment pathways of 1,285 DEGs indicated that 22 DEGs encoding cell wall modifications and hydrolases associated with pod shattering were highly expressed in shattering-susceptible accessions. These genes were mainly enriched in “hydrolase activity,” “cytoplasm,” and “carbohydrate metabolic process” systems. These cell wall modifications and hydrolases genes included β-glucosidase and endo-polygalacturonase, which work together to break down the glycosidic bonds of pectin and cellulose, and to promote the dissolution and disappearance of the cell wall in the ventral suture of the pod and make the pod more susceptible to shattering. We demonstrated the differences in gene transcription levels between the shattering-susceptible and shattering-resistant vetch accessions for the first time and our results provided valuable information for the identifying and characterizing of pod shattering regulation networks in vetch. This information may facilitate the future identification of pod shattering-related genes and their underlying molecular mechanisms in the common vetch.

Background Elymus L. is the largest genus in the tribe Triticeae Dumort., encompassing approximately 150 polyploid perennial species widely distributed in the temperate regions of the world. It is considered to be an important gene pool for improving cereal crops. However, a shortage of molecular marker limits the efficiency and accuracy of genetic breeding for Elymus species. High-throughput transcriptome sequencing data is essential for gene discovery and molecular marker development. Results We obtained the transcriptome dataset of E. sibiricus, the type species of the genus Elymus, and identified a total of 8871 putative EST-SSRs from 6685 unigenes. Trinucleotides were the dominant repeat motif (4760, 53.66%), followed by dinucleotides (1993, 22.47%) and mononucleotides (1876, 21.15%). The most dominant trinucleotide repeat motif was CCG/CGG (1119, 23.5%). Sequencing of PCR products showed that the sequenced alleles from different Elymus species were homologous to the original SSR locus from which the primer was designed. Different types of tri-repeats as abundant SSR motifs were observed in repeat regions. Two hundred EST-SSR primer pairs were designed and selected to amplify ten DNA samples of Elymus species. Eighty-seven pairs of primer (43.5%) generated clear and reproducible bands with expected size, and showed good transferability across different Elymus species. Finally, thirty primer pairs successfully amplified ninety-five accessions of seventeen Elymus species, and detected significant amounts of polymorphism. In general, hexaploid Elymus species with genomes StStHHYY had a relatively higher level of genetic diversity (H = 0.219, I = 0.330, % P = 63.7), while tetraploid Elymus species with genomes StStYY had low level of genetic diversity (H = 0.182, I = 0.272, % P = 50.4) in the study. The cluster analysis showed that all ninety-five accessions were clustered into three major clusters. The accessions were grouped mainly according to their genomic components and origins. Conclusions This study demonstrated that transcriptome sequencing is a fast and cost-effective approach to molecular marker development. These EST-SSR markers developed in this study are valuable tools for genetic diversity, evolutionary, and molecular breeding in E. sibiricus , and other Elymus species. Electronic supplementary material The online version of this article (10.1186/s12870-019-1825-8) contains supplementary material, which is available to authorized users.

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Background: Elymus sibiricus is an important forage grass in semi-arid regions, but it is difficult to grow for commercial seed production due to high seed shattering. To better understand the underlying mechanism and explore the putative genes related to seed shattering, we conducted a combination of morphological, histological, physiochemical and transcriptome analysis on two E. sibiricus genotypes (XH09 and ZhN03) that have contrasting seed shattering.

Rapid and sensitive detection of SARS associated coronavirus is critical for early diagnosis and control of severe acute respiratory syndrome. This study describes a method for the detection of SARS associated coronavirus gene by the combination of functionalized nanoparticles and PCR-based assay. In this method, the target cDNA of SARS associated coronavirus was firstly captured and enriched from the mixture of target cDNA and non-target cDNA by the use of the functionalized silica coated superparamagnetic nanoparticles. Additionally, the enriched target cDNA were amplified through a general symmetry PCR and then was selectively isolated from the double strands PCR products by applying the silica coated superparamagnetic nanoparticles again. Finally, we detected the amplified target cDNA by employing the functionalized silica coated fluorescent nanoparticles as signaling probes with a sandwich hybridization format. The results show that the target cDNA can be assayed successfully with a detection limit of 2.0 × 103 copies and the nonspecific amplification could be inhibited. In addition, the detection procedure is rapid and can be completed in less than 6 h. Our results suggest that this approach will provide promising prospects for other pathogens detection.