Cotton is one of the most economically important crop plants worldwide. Its fiber, commonly known as cotton lint, is the principal natural source for the textile industry. Approximately 33 million ha (5% of the world's arable land) is used for cotton planting 1 , with an annual global market value of textile mills of approximately $630.6 billion in 2011 (MarketPublishers; see URLs). Apart from its economic value, cotton is also an excellent model system for studying polyploidization, cell elongation and cell wall biosynthesis 2-5 .The Gossypium genus contains 5 tetraploid (AD 1 to AD 5 , 2n = 4×) and over 45 diploid (2n = 2×) species (where n is the number of chromosomes in the gamete of an individual), which are believed to have originated from a common ancestor approximately 5-10 million years ago 6 . Eight diploid subgenomes, designated as A to G and K, have been found across North America, Africa, Asia and Australia. The haploid genome size of diploid cottons (2n = 2× = 26) varies from about 880 Mb (G. raimondii Ulbrich) in the D genome to 2,500 Mb in the K genome 7,8 . Diploid cotton species share a common chromosome number (n = 13), and high levels of synteny or colinearity are observed among them 9-12 . The tetraploid cotton species (2n = 4× = 52), such as G. hirsutum L. and Gossypium barbadense L., are thought to have formed by an allopolyploidization event that occurred approximately 1-2 million years ago, which involved a D-genome species as the pollen-providing parent and an A-genome species as the maternal parent 13,14 . To gain insights into the cultivated polyploid genomes-how they have evolved and how their subgenomes interact-it is first necessary to have a basic knowledge of the structure of the component genomes. Therefore, we have created a draft sequence of the putative D-genome parent, G. raimondii, using DNA samples prepared from Cotton Microsatellite Database (CMD) 10 (refs. 15,16), a genetic standard originated from a single seed (accession D 5 -3) in 2004 and brought to near homozygosity by six successive generations of self-fertilization. We believe that sequencing of the G. raimondii genome will not only provide a major source of candidate genes important for the genetic improvement of cotton quality and productivity, but it may also serve as a reference for the assembly of the tetraploid G. hirsutum genome. RESULTS Sequencing and assemblyA whole-genome shotgun strategy was used to sequence and assemble the G. raimondii genome. A total of 78.7 Gb of next-generation Illumina paired-end 50-bp, 100-bp and 150-bp reads was generated by sequencing genome shotgun libraries of different fragment lengths (170 bp, 250 bp, 500 bp, 800 bp, 2 kb, 5 kb, 10 kb, 20 kb and 40 kb) that covered 103.6-fold of the 775.2-Mb assembled G. raimondii genome (Supplementary Table 1). The resulting assembly appeared to cover a very large proportion of the euchromatin of the G. raimondii genome. The unassembled genomic regions are likely to contain heterochromatic satellites, large repetitive sequences or ribosoma...

The draft genome of the pear (Pyrus bretschneideri) using a combination of BAC-by-BAC and next-generation sequencing is reported. A 512.0-Mb sequence corresponding to 97.1% of the estimated genome size of this highly heterozygous species is assembled with 1943 coverage. High-density genetic maps comprising 2005 SNP markers anchored 75.5% of the sequence to all 17 chromosomes. The pear genome encodes 42,812 protein-coding genes, and of these,~28.5% encode multiple isoforms. Repetitive sequences of 271.9 Mb in length, accounting for 53.1% of the pear genome, are identified. Simulation of eudicots to the ancestor of Rosaceae has reconstructed nine ancestral chromosomes. Pear and apple diverged from each other~5.4-21.5 million years ago, and a recent whole-genome duplication (WGD) event must have occurred 30-45 MYA prior to their divergence, but following divergence from strawberry. When compared with the apple genome sequence, size differences between the apple and pear genomes are confirmed mainly due to the presence of repetitive sequences predominantly contributed by transposable elements (TEs), while genic regions are similar in both species. Genes critical for self-incompatibility, lignified stone cells (a unique feature of pear fruit), sorbitol metabolism, and volatile compounds of fruit have also been identified. Multiple candidate SFB genes appear as tandem repeats in the S-locus region of pear; while lignin synthesis-related gene family expansion and highly expressed gene families of HCT, C39H, and CCOMT contribute to high accumulation of both G-lignin and S-lignin. Moreover, alpha-linolenic acid metabolism is a key pathway for aroma in pear fruit.

WGS can provide comprehensive resistance genotypes and is capable of accurately predicting resistance phenotypes, making it a valuable tool for surveillance. Moreover, the data presented here showing the ability to accurately predict resistance suggest that WGS may be used as a screening tool in selecting anti-infective therapy, especially as costs drop and methods improve.

BackgroundThe oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most economically important pests in the world, causing serious damage to fruit production. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its development and its ability to resist insecticides. Analysis of the B. dorsalis transcriptome and its expression profile data is essential to extending the genetic information resources on this species, providing a shortcut that will support studies on B. dorsalis.Methodology/Principal FindingsWe performed de novo assembly of a transcriptome using short read sequencing technology (Illumina). The results generated 484,628 contigs, 70,640 scaffolds, and 49,804 unigenes. Of those unigenes, 27,455 (55.13%) matched known proteins in the NCBI database, as determined by BLAST search. Clusters of orthologous groups (COG), gene orthology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations were performed to better understand the functions of these unigenes. Genes related to insecticide resistance were analyzed in additional detail. Digital gene expression (DGE) libraries showed differences in gene expression profiles at different developmental stages (eggs, third-instar larvae, pupae, and adults). To confirm the DGE results, the expression profiles of six randomly selected genes were analyzed.Conclusion/SignificanceThis transcriptome greatly improves our genetic understanding of B. dorsalis and makes a huge number of gene sequences available for further study, including both genes of known importance and genes of unknown function. The DGE data provide comprehensive insight into gene expression profiles at different developmental stages. This facilitates the study of the role of each gene in the developmental process and in insecticide resistance.