A chromosome-scale genome assembly of European hazel (Corylus avellana L.) reveals targets for crop improvement.

The European hazelnut (Corylus avellana L.) is a tree crop of economic importance worldwide, but especially for northern Turkey, where the majority of production takes place. Hazelnut production is currently challenged by environmental stresses, such as a recent outbreak of severe powdery mildew disease; furthermore, allergy to hazelnuts is an increasing health concern in some regions. In order to provide a foundation for using the available hazelnut genetic resources for crop improvement, we produced a fully assembled genome sequence and annotation for a hazelnut species, from C. avellana cv. 'Tombul', one of the most important Turkish varieties. A hybrid sequencing strategy, combining short reads, long reads and proximity ligation methods, enabled us to resolve heterozygous regions and produce a high-quality 370-Mb assembly that agrees closely with cytogenetic studies and genetic maps of the 11 C. avellana chromosomes, and covers 97.8% of the estimated genome size. The genome includes 27 270 high-confidence protein-coding genes, over 20 000 of which were functionally annotated based on homology with known plant proteins. We focused particularly on gene families encoding hazelnut allergens, and the Mildew resistance Locus O (MLO) proteins that are an important susceptibility factor for powdery mildew. The complete assembly enabled us to differentiate between members of these families and to identify homologues that may be important in mildew disease and hazelnut allergy. These findings provide examples of how the genome can be used to guide research and to develop effective strategies for crop improvement in C. avellana.

Comparison of different annotation tools for characterization of the complete chloroplast genome of Corylus avellana cv Tombul.

BACKGROUND: Several bioinformatics tools have been designed for assembly and annotation of chloroplast (cp) genomes, making it difficult to decide which is most useful and applicable to a specific case. The increasing number of plant genomes provide an opportunity to accurately obtain cp genomes from whole genome shotgun (WGS) sequences. Due to the limited genetic information available for European hazelnut (Corylus avellana L.) and as part of a genome sequencing project, we analyzed the complete chloroplast genome of the cultivar 'Tombul' with multiple annotation tools. RESULTS: Three different annotation strategies were tested, and the complete cp genome of C. avellana cv Tombul was constructed, which was 161,667 bp in length, and had a typical quadripartite structure. A large single copy (LSC) region of 90,198 bp and a small single copy (SSC) region of 18,733 bp were separated by a pair of inverted repeat (IR) regions of 26,368 bp. In total, 125 predicted functional genes were annotated, including 76 protein-coding, 25 tRNA, and 4 rRNA unique genes. Comparative genomics indicated that the cp genome sequences were relatively highly conserved in species belonging to the same order. However, there were still some variations, especially in intergenic regions, that could be used as molecular markers for analyses of phylogeny and plant identification. Simple sequence repeat (SSR) analysis showed that there were 83 SSRs in the cp genome of cv Tombul. Phylogenetic analysis suggested that C. avellana cv Tombul had a close affinity to the sister group of C. fargesii and C. chinensis, and then a closer evolutionary relationship with Betulaceae family than other species of Fagales. CONCLUSION: In this study, the complete cp genome of Corylus avellana cv Tombul, the most widely cultivated variety in Turkey, was obtained and annotated, and additionally phylogenetic relationships were predicted among Fagales species. Our results suggest a very accurate assembly of chloroplast genome from next generation whole genome shotgun (WGS) sequences. Enhancement of taxon sampling in Corylus species provide genomic insights into phylogenetic analyses. The nucleotide sequences of cv Tombul cp genomes can provide comprehensive genetic insight into the evolution of genus Corylus.

The prognostic value of circulating microRNAs in heart failure: preliminary results from a genome-wide expression study.

INTRODUCTION: Recent studies have demonstrated the potential of microRNAs (miRNA) as biomarkers in various cardiovascular disorders. The aim of the present study was to quantitatively evaluate the expression levels of miRNAs in patients with chronic congestive heart failure (CHF) in order to identify differential expression profiles as biomarkers with prognostic values. MATERIALS AND METHOD: The study included 20 clinically stable [New York Heart Association (NYHA) II] and 22 decompensated (NYHA III and IV) CHF patients and 15 healthy controls. miRNA profiling was performed using a microarray method. Dysregulated miRNAs were evaluated for their biomarker potential. RESULTS: Microarray profiling revealed an increase in the expression of miR-21, miR-650, miR-744, miR-516-5p, miR-1292, miR-182, miR-1228, miR-595, miR-663b, miR-1296, miR-1825, miR-299-3p, miR-662 miR-122, miR-3148 and miR-518e and a decrease in the expression of miR-129-3p, miR-3155, miR-3175, miR-583, miR-568, miR-30d, miR-200a-star, miR-1979, miR-371-3p, miR-155-star and miR-502-5p in sera of CHF patients. The prognostic value of miR-182 [area under the curve (AUC) 0.695] was found to be superior to pro-brain type natriuretic peptide (NT-proBNP; AUC 0.350) and high-sensitivity C-reactive protein (hs-CRP) (AUC 0.475) by receiver operator characteristic (ROC) analysis. Cox regression analysis showed that miR-182 could predict cardiovascular mortality (P = 0.032). CONCLUSION: We demonstrated the increased expression levels of circulating miRNAs in CHF as compared with controls. Moreover, miR-182 was found to be a potential prognostic marker in CHF.