Chun-Huai Cheng

The Genome Database for Rosaceae (GDR): year 10 update

The Genome Database for Rosaceae (GDR, http:/www.rosaceae.org), the long-standing central repository and data mining resource for Rosaceae research, has been enhanced with new genomic, genetic and breeding data, and improved functionality. Whole genome sequences of apple, peach and strawberry are available to browse or download with a range of annotations, including gene model predictions, aligned transcripts, repetitive elements, polymorphisms, mapped genetic markers, mapped NCBI Rosaceae genes, gene homologs and association of InterPro protein domains, GO terms and Kyoto Encyclopedia of Genes and Genomes pathway terms. Annotated sequences can be queried using search interfaces and visualized using GBrowse. New expressed sequence tag unigene sets are available for major genera, and Pathway data are available through FragariaCyc, AppleCyc and PeachCyc databases. Synteny among the three sequenced genomes can be viewed using GBrowse_Syn. New markers, genetic maps and extensively curated qualitative/Mendelian and quantitative trait loci are available. Phenotype and genotype data from breeding projects and genetic diversity projects are also included. Improved search pages are available for marker, trait locus, genetic diversity and publication data. New search tools for breeders enable selection comparison and assistance with breeding decision making.

CottonGen: a genomics, genetics and breeding database for cotton research

CottonGen (http://www.cottongen.org) is a curated and integrated web-based relational database providing access to publicly available genomic, genetic and breeding data for cotton. CottonGen supercedes CottonDB and the Cotton Marker Database, with enhanced tools for easier data sharing, mining, visualization and data retrieval of cotton research data. CottonGen contains annotated whole genome sequences, unigenes from expressed sequence tags (ESTs), markers, trait loci, genetic maps, genes, taxonomy, germplasm, publications and communication resources for the cotton community. Annotated whole genome sequences of Gossypium raimondii are available with aligned genetic markers and transcripts. These whole genome data can be accessed through genome pages, search tools and GBrowse, a popular genome browser. Most of the published cotton genetic maps can be viewed and compared using CMap, a comparative map viewer, and are searchable via map search tools. Search tools also exist for markers, quantitative trait loci (QTLs), germplasm, publications and trait evaluation data. CottonGen also provides online analysis tools such as NCBI BLAST and Batch BLAST.

Chestnut resistance to the blight disease: insights from transcriptome analysis

BackgroundA century ago, Chestnut Blight Disease (CBD) devastated the American chestnut. Backcross breeding has been underway to introgress resistance from Chinese chestnut into surviving American chestnut genotypes. Development of genomic resources for the family Fagaceae, has focused in this project on Castanea mollissima Blume (Chinese chestnut) and Castaneadentata (Marsh.) Borkh (American chestnut) to aid in the backcross breeding effort and in the eventual identification of blight resistance genes through genomic sequencing and map based cloning. A previous study reported partial characterization of the transcriptomes from these two species. Here, further analyses of a larger dataset and assemblies including both 454 and capillary sequences were performed and defense related genes with differential transcript abundance (GDTA) in canker versus healthy stem tissues were identified.ResultsOver one and a half million cDNA reads were assembled into 34,800 transcript contigs from American chestnut and 48,335 transcript contigs from Chinese chestnut. Chestnut cDNA showed higher coding sequence similarity to genes in other woody plants than in herbaceous species. The number of genes tagged, the length of coding sequences, and the numbers of tagged members within gene families showed that the cDNA dataset provides a good resource for studying the American and Chinese chestnut transcriptomes. In silico analysis of transcript abundance identified hundreds of GDTA in canker versus healthy stem tissues. A significant number of additional DTA genes involved in the defense-response not reported in a previous study were identified here. These DTA genes belong to various pathways involving cell wall biosynthesis, reactive oxygen species (ROS), salicylic acid (SA), ethylene, jasmonic acid (JA), abscissic acid (ABA), and hormone signalling. DTA genes were also identified in the hypersensitive response and programmed cell death (PCD) pathways. These DTA genes are candidates for host resistance to the chestnut blight fungus, Cryphonectria parasitica.ConclusionsOur data allowed the identification of many genes and gene network candidates for host resistance to the chestnut blight fungus, Cryphonectria parasitica. The similar set of GDTAs in American chestnut and Chinese chestnut suggests that the variation in sensitivity to this pathogen between these species may be the result of different timing and amplitude of the response of the two to the pathogen infection. Resources developed in this study are useful for functional genomics, comparative genomics, resistance breeding and phylogenetics in the Fagaceae.

Tripal: a construction toolkit for online genome databases

As the availability, affordability and magnitude of genomics and genetics research increases so does the need to provide online access to resulting data and analyses. Availability of a tailored online database is the desire for many investigators or research communities; however, managing the Information Technology infrastructure needed to create such a database can be an undesired distraction from primary research or potentially cost prohibitive. Tripal provides simplified site development by merging the power of Drupal, a popular web Content Management System with that of Chado, a community-derived database schema for storage of genomic, genetic and other related biological data. Tripal provides an interface that extends the content management features of Drupal to the data housed in Chado. Furthermore, Tripal provides a web-based Chado installer, genomic data loaders, web-based editing of data for organisms, genomic features, biological libraries, controlled vocabularies and stock collections. Also available are Tripal extensions that support loading and visualizations of NCBI BLAST, InterPro, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses, as well as an extension that provides integration of Tripal with GBrowse, a popular GMOD tool. An Application Programming Interface is available to allow creation of custom extensions by site developers, and the look-and-feel of the site is completely customizable through Drupal-based PHP template files. Addition of non-biological content and user-management is afforded through Drupal. Tripal is an open source and freely available software package found at http://tripal.sourceforge.net

A physical map of the Chinese chestnut (Castanea mollissima) genome and its integration with the genetic map

Three Chinese chestnut bacterial artificial chromosome (BAC) libraries were developed and used for physical map construction. Specifically, high information content fingerprinting was used to assemble 126,445 BAC clones into 1,377 contigs and 12,919 singletons. Integration of the dense Chinese chestnut genetic map with the physical map was achieved via high-throughput hybridization using overgo probes derived from sequence-based genetic markers. A total of 1,026 probes were anchored to the physical map including 831 probes corresponding to 878 expressed sequence tag-based markers. Within the physical map, three BAC contigs were anchored to the three major fungal blight-resistant quantitative trait loci on chestnut linkage groups B, F, and G. A subset of probes corresponding to orthologous genes in poplar showed only a limited amount of conserved gene order between the poplar and chestnut genomes. The integrated genetic and physical map of Chinese chestnut is available at www.fagaceae.org/physical_maps.

Tripal v1.1: a standards-based toolkit for construction of online genetic and genomic databases

Tripal is an open-source freely available toolkit for construction of online genomic and genetic databases. It aims to facilitate development of community-driven biological websites by integrating the GMOD Chado database schema with Drupal, a popular website creation and content management software. Tripal provides a suite of tools for interaction with a Chado database and display of content therein. The tools are designed to be generic to support the various ways in which data may be stored in Chado. Previous releases of Tripal have supported organisms, genomic libraries, biological stocks, stock collections and genomic features, their alignments and annotations. Also, Tripal and its extension modules provided loaders for commonly used file formats such as FASTA, GFF, OBO, GAF, BLAST XML, KEGG heir files and InterProScan XML. Default generic templates were provided for common views of biological data, which could be customized using an open Application Programming Interface to change the way data are displayed. Here, we report additional tools and functionality that are part of release v1.1 of Tripal. These include (i) a new bulk loader that allows a site curator to import data stored in a custom tab delimited format; (ii) full support of every Chado table for Drupal Views (a powerful tool allowing site developers to construct novel displays and search pages); (iii) new modules including ‘Feature Map’, ‘Genetic’, ‘Publication’, ‘Project’, ‘Contact’ and the ‘Natural Diversity’ modules. Tutorials, mailing lists, download and set-up instructions, extension modules and other documentation can be found at the Tripal website located at http://tripal.info. Database URL: http://tripal.info/

Complete genome of the onion pathogen Enterobacter cloacae EcWSU1

Previous studies have shown that the members of the Enterobacter cloacae complex are difficult to differentiate with biochemical tests and in phylogenetic studies using multilocus sequence analysis, strains of the same species separate into numerous clusters. There are only a few complete E. cloacae genome sequences and very little knowledge about the mechanism of pathogenesis of E. cloacae on plants and humans. Enterobacter cloacae EcWSU1 causes Enterobacter bulb decay in stored onions (Allium cepa). The EcWSU1 genome consists of a 4,734,438 bp chromosome and a mega-plasmid of 63,653 bp. The chromosome has 4,632 protein coding regions, 83 tRNA sequences, and 8 rRNA operons.

Sequencing of a QTL-rich region of the Theobroma cacao genome using pooled BACs and the identification of trait specific candidate genes

BackgroundBAC-based physical maps provide for sequencing across an entire genome or a selected sub-genomic region of biological interest. Such a region can be approached with next-generation whole-genome sequencing and assembly as if it were an independent small genome. Using the minimum tiling path as a guide, specific BAC clones representing the prioritized genomic interval are selected, pooled, and used to prepare a sequencing library.ResultsThis pooled BAC approach was taken to sequence and assemble a QTL-rich region, of ~3 Mbp and represented by twenty-seven BACs, on linkage group 5 of the Theobroma cacao cv. Matina 1-6 genome. Using various mixtures of read coverages from paired-end and linear 454 libraries, multiple assemblies of varied quality were generated. Quality was assessed by comparing the assembly of 454 reads with a subset of ten BACs individually sequenced and assembled using Sanger reads. A mixture of reads optimal for assembly was identified. We found, furthermore, that a quality assembly suitable for serving as a reference genome template could be obtained even with a reduced depth of sequencing coverage. Annotation of the resulting assembly revealed several genes potentially responsible for three T. cacao traits: black pod disease resistance, bean shape index, and pod weight.ConclusionsOur results, as with other pooled BAC sequencing reports, suggest that pooling portions of a minimum tiling path derived from a BAC-based physical map is an effective method to target sub-genomic regions for sequencing. While we focused on a single QTL region, other QTL regions of importance could be similarly sequenced allowing for biological discovery to take place before a high quality whole-genome assembly is completed.

A standard nomenclature for gene designation in the Rosaceae

The plant family Rosaceae is comprised of a highly diverse group of plants, with a wide range of ornamental and agricultural uses throughout the world. Comparative genomic analyses between rosaceous species are increasingly being used to assign putative function. With the wealth of new data, there is a need to standardize nomenclature to ensure uniformity and clarity across research groups. The Rosaceae Gene Name Standardization Committee was formed to develop a naming guideline for genes in Rosaceae family members. This manuscript details the issues involved with naming genes and proposes a common nomenclature system. The Genome Database for Rosaceae (GDR) (www.rosaceae.org) has developed a gene database that will support user-submitted gene names and annotations in addition to the predicted genes from whole genome sequences. GDR also hosts user-curated lists of gene class symbols. To facilitate standardization of gene names and avoid misinterpretation, the committee recommends that the GDR serve as the database of record for the names of Rosaceae genes and that gene names, gene class symbols, and gene annotation be registered in GDR prior to publication in peer reviewed journals.

Chado use case: storing genomic, genetic and breeding data of Rosaceae and Gossypium crops in Chado

The Genome Database for Rosaceae (GDR) and CottonGen are comprehensive online data repositories that provide access to integrated genomic, genetic and breeding data through search, visualization and analysis tools for Rosaceae crops and Gossypium (cotton). These online databases use Chado, an open-source, generic and ontology-driven database schema for biological data, as the primary data storage platform. Chado is highly normalized and uses ontologies to indicate the ‘types’ of data. Therefore, Chado is flexible such that it has been used to house genomic, genetic and breeding data for GDR and CottonGen. These data include whole genome sequence and annotation, transcripts, molecular markers, genetic maps, Quantitative Trait Loci, Mendelian Trait Loci, traits, germplasm, pedigrees, large scale phenotypic and genotypic data, ontologies and publications. We provide information about how to store these types of data in Chado using GDR and CottonGen as examples sites that were converted from an older legacy infrastructure. Database URL: GDR (www.rosaceae.org), CottonGen (www.cottongen.org)