5 7Carrot (Daucus carota subsp. carota L.; 2n = 2x = 18) is a globally important root crop whose production has quadrupled between 1976 and 2013 (FAO Statistics; see URLs), outpacing the overall rate of increase in vegetable production and world population growth (FAO Statistics; see URLs) through development of high-value products for fresh consumption, juices, and natural pigments and cultivars adapted to warmer production regions 1 .The first documented colors for domesticated carrot root were yellow and purple in Central Asia approximately 1,100 years ago 2,3 , with orange carrots not reliably reported until the sixteenth century in Europe 4,5 . The popularity of orange carrots is fortuitous for modern consumers because the orange pigmentation results from high quantities of alpha-and beta-carotene, making carrots the richest source of provitamin A in the US diet 6 . Carrot breeding has substantially increased nutritional value, with a 50% average increase in carotene content in the United States as compared to 40 years ago 6 . Lycopene and lutein in red and yellow carrots, respectively, are also nutritionally important carotenoids, making carrot a model system to study storage root development and carotenoid accumulation.Carrot is the most important crop in the Apiaceae family, which includes numerous other vegetables, herbs, spices, and medicinal plants that enhance the epicurean experience 7 , including celery, parsnip, arracacha, parsley, fennel, coriander, and cumin. The Apiaceae family belongs to the euasterid II clade, which includes important crops such as lettuce and sunflower 8 . Genome sequences of euasterid I species have been reported, but only two genomes 9,10 have been published among the other euasterid II species.Here we report a high-quality genome assembly of a doubledhaploid orange carrot, characterization of the mechanism controlling carotenoid accumulation in storage roots, and the resequencing of 35 accessions spanning the genetic diversity of the Daucus genus. Our comprehensive genomic analyses provide insights into the evolution of the asterids and several gene families. These results will facilitate biological discovery and crop improvement in carrot and other crops.A high-quality carrot genome assembly provides new insights into carotenoid accumulation and asterid genome evolution We report a high-quality chromosome-scale assembly and analysis of the carrot (Daucus carota) genome, the first sequenced genome to include a comparative evolutionary analysis among members of the euasterid II clade. We characterized two new polyploidization events, both occurring after the divergence of carrot from members of the Asterales order, clarifying the evolutionary scenario before and after radiation of the two main asterid clades. Large- and small-scale lineage-specific duplications have contributed to the expansion of gene families, including those with roles in flowering time, defense response, flavor, and pigment accumulation. We identified a candidate gene, DCAR_032551, that conditions caro...

Orchidaceae, renowned for its spectacular flowers and other reproductive and ecological adaptations, is one of the most diverse plant families. Here we present the genome sequence of the tropical epiphytic orchid Phalaenopsis equestris, a frequently used parent species for orchid breeding. P. equestris is the first plant with crassulacean acid metabolism (CAM) for which the genome has been sequenced. Our assembled genome contains 29,431 predicted protein-coding genes. We find that contigs likely to be underassembled, owing to heterozygosity, are enriched for genes that might be involved in self-incompatibility pathways. We find evidence for an orchid-specific paleopolyploidy event that preceded the radiation of most orchid clades, and our results suggest that gene duplication might have contributed to the evolution of CAM photosynthesis in P. equestris. Finally, we find expanded and diversified families of MADS-box C/D-class, B-class AP3 and AGL6-class genes, which might contribute to the highly specialized morphology of orchid flowers

BackgroundThe assessment and characterization of the gut microbiome has become a focus of research in the area of human autoimmune diseases. Ankylosing spondylitis is an inflammatory autoimmune disease and evidence showed that ankylosing spondylitis may be a microbiome-driven disease.ResultsTo investigate the relationship between the gut microbiome and ankylosing spondylitis, a quantitative metagenomics study based on deep shotgun sequencing was performed, using gut microbial DNA from 211 Chinese individuals. A total of 23,709 genes and 12 metagenomic species were shown to be differentially abundant between ankylosing spondylitis patients and healthy controls. Patients were characterized by a form of gut microbial dysbiosis that is more prominent than previously reported cases with inflammatory bowel disease. Specifically, the ankylosing spondylitis patients demonstrated increases in the abundance of Prevotella melaninogenica, Prevotella copri, and Prevotella sp. C561 and decreases in Bacteroides spp. It is noteworthy that the Bifidobacterium genus, which is commonly used in probiotics, accumulated in the ankylosing spondylitis patients. Diagnostic algorithms were established using a subset of these gut microbial biomarkers.ConclusionsAlterations of the gut microbiome are associated with development of ankylosing spondylitis. Our data suggest biomarkers identified in this study might participate in the pathogenesis or development process of ankylosing spondylitis, providing new leads for the development of new diagnostic tools and potential treatments.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-017-1271-6) contains supplementary material, which is available to authorized users.

The Brassicaceae, including Arabidopsis thaliana and Brassica crops, is unmatched among plants in its wealth of genomic and functional molecular data and has long served as a model for understanding gene, genome, and trait evolution. However, genome information from a phylogenetic outgroup that is essential for inferring directionality of evolutionary change has been lacking. We therefore sequenced the genome of the spider flower (Tarenaya hassleriana) from the Brassicaceae sister family, the Cleomaceae. By comparative analysis of the two lineages, we show that genome evolution following ancient polyploidy and gene duplication events affect reproductively important traits. We found an ancient genome triplication in Tarenaya (Th-a) that is independent of the Brassicaceae-specific duplication (At-a) and nested Brassica (Br-a) triplication. To showcase the potential of sister lineage genome analysis, we investigated the state of floral developmental genes and show Brassica retains twice as many floral MADS (for MINICHROMOSOME MAINTENANCE1, AGAMOUS, DEFICIENS and SERUM RESPONSE FACTOR) genes as Tarenaya that likely contribute to morphological diversity in Brassica. We also performed synteny analysis of gene families that confer self-incompatibility in Brassicaceae and found that the critical SERINE RECEPTOR KINASE receptor gene is derived from a lineage-specific tandem duplication. The T. hassleriana genome will facilitate future research toward elucidating the evolutionary history of Brassicaceae genomes.

BackgroundRecently, many studies utilizing next generation sequencing have investigated plant evolution and domestication in annual crops. Peach, Prunus persica, is a typical perennial fruit crop that has ornamental and edible varieties. Unlike other fruit crops, cultivated peach includes a large number of phenotypes but few polymorphisms. In this study, we explore the genetic basis of domestication in peach and the influence of humans on its evolution.ResultsWe perform large-scale resequencing of 10 wild and 74 cultivated peach varieties, including 9 ornamental, 23 breeding, and 42 landrace lines. We identify 4.6 million SNPs, a large number of which could explain the phenotypic variation in cultivated peach. Population analysis shows a single domestication event, the speciation of P. persica from wild peach. Ornamental and edible peach both belong to P. persica, along with another geographically separated subgroup, Prunus ferganensis.We identify 147 and 262 genes under edible and ornamental selection, respectively. Some of these genes are associated with important biological features. We perform a population heterozygosity analysis in different plants that indicates that free recombination effects could affect domestication history. By applying artificial selection during the domestication of the peach and facilitating its asexual propagation, humans have caused a sharp decline of the heterozygote ratio of SNPs.ConclusionsOur analyses enhance our knowledge of the domestication history of perennial fruit crops, and the dataset we generated could be useful for future research on comparative population genomics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-014-0415-1) contains supplementary material, which is available to authorized users.