TitleThe genome of wine yeast Dekkera bruxellensis provides a tool to explore its food-related properties

Nicotine, the signature alkaloid of Nicotiana species responsible for the addictive properties of human tobacco smoking, functions as a defensive neurotoxin against attacking herbivores. However, the evolution of the genetic features that contributed to the assembly of the nicotine biosynthetic pathway remains unknown. We sequenced and assembled genomes of two wild tobaccos, Nicotiana attenuata (2.5 Gb) and Nicotiana obtusifolia (1.5 Gb), two ecological models for investigating adaptive traits in nature. We show that after the Solanaceae whole-genome triplication event, a repertoire of rapidly expanding transposable elements (TEs) bloated these Nicotiana genomes, promoted expression divergences among duplicated genes, and contributed to the evolution of herbivoryinduced signaling and defenses, including nicotine biosynthesis. The biosynthetic machinery that allows for nicotine synthesis in the roots evolved from the stepwise duplications of two ancient primary metabolic pathways: the polyamine and nicotinamide adenine dinucleotide (NAD) pathways. In contrast to the duplication of the polyamine pathway that is shared among several solanaceous genera producing polyamine-derived tropane alkaloids, we found that lineage-specific duplications within the NAD pathway and the evolution of rootspecific expression of the duplicated Solanaceae-specific ethylene response factor that activates the expression of all nicotine biosynthetic genes resulted in the innovative and efficient production of nicotine in the genus Nicotiana. Transcription factor binding motifs derived from TEs may have contributed to the coexpression of nicotine biosynthetic pathway genes and coordinated the metabolic flux. Together, these results provide evidence that TEs and gene duplications facilitated the emergence of a key metabolic innovation relevant to plant fitness.Nicotiana genomes | genome-wide multiplications | transposable elements | nicotine biosynthesis | expression divergence

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). Accession numbers: The RNA-seq data for generating the results in this study are deposited in NCBI short reads archive under the Bio Project ID (PRJNA223344), the sequences of genes that were selected for alternative splicing and expression analysis has been deposited at DDBJ/EMBL/GenBank under the accession GCZL01000000. SUMMARYChanges in gene expression and alternative splicing (AS) are involved in many responses to abiotic and biotic stresses in eukaryotic organisms. In response to attack and oviposition by insect herbivores, plants elicit rapid changes in gene expression which are essential for the activation of plant defenses; however, the herbivory-induced changes in AS remain unstudied. Using mRNA sequencing, we performed a genomewide analysis on tobacco hornworm (Manduca sexta) feeding-induced AS in both leaves and roots of Nicotiana attenuata. Feeding by M. sexta for 5 h reduced total AS events by 7.3% in leaves but increased them in roots by 8.0% and significantly changed AS patterns in leaves and roots of existing AS genes. Feeding by M. sexta also resulted in increased (in roots) and decreased (in leaves) transcript levels of the serine/arginine-rich (SR) proteins that are involved in the AS machinery of plants and induced changes in SR gene expression that were jasmonic acid (JA)-independent in leaves but JA-dependent in roots. Changes in AS and gene expression elicited by M. sexta feeding were regulated independently in both tissues. This study provides genome-wide evidence that insect herbivory induces changes not only in the levels of gene expression but also in their splicing, which might contribute to defense against and/or tolerance of herbivory.

Background Nicotiana attenuata (coyote tobacco) is an ecological model for studying plant-environment interactions and plant gene function under real-world conditions. During the last decade, large amounts of genomic, transcriptomic and metabolomic data have been generated with this plant which has provided new insights into how native plants interact with herbivores, pollinators and microbes. However, an integrative and open access platform that allows for the efficient mining of these -omics data remained unavailable until now.DescriptionWe present the Nicotiana attenuata Data Hub (NaDH) as a centralized platform for integrating and visualizing genomic, phylogenomic, transcriptomic and metabolomic data in N. attenuata. The NaDH currently hosts collections of predicted protein coding sequences of 11 plant species, including two recently sequenced Nicotiana species, and their functional annotations, 222 microarray datasets from 10 different experiments, a transcriptomic atlas based on 20 RNA-seq expression profiles and a metabolomic atlas based on 895 metabolite spectra analyzed by mass spectrometry. We implemented several visualization tools, including a modified version of the Electronic Fluorescent Pictograph (eFP) browser, co-expression networks and the Interactive Tree Of Life (iTOL) for studying gene expression divergence among duplicated homologous. In addition, the NaDH allows researchers to query phylogenetic trees of 16,305 gene families and provides tools for analyzing their evolutionary history. Furthermore, we also implemented tools to identify co-expressed genes and metabolites, which can be used for predicting the functions of genes. Using the transcription factor NaMYB8 as an example, we illustrate that the tools and data in NaDH can facilitate identification of candidate genes involved in the biosynthesis of specialized metabolites.ConclusionThe NaDH provides interactive visualization and data analysis tools that integrate the expression and evolutionary history of genes in Nicotiana, which can facilitate rapid gene discovery and comparative genomic analysis. Because N. attenuata shares many genome-wide features with other Nicotiana species including cultivated tobacco, and hence NaDH can be a resource for exploring the function and evolution of genes in Nicotiana species in general. The NaDH can be accessed at: http://nadh.ice.mpg.de/.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3465-9) contains supplementary material, which is available to authorized users.