Chromosome-scale genome assembly of the transformation-amenable common wheat cultivar ‘Fielder’

We have established a high-quality, chromosome-level genome assembly for the hexaploid common wheat cultivar ‘Fielder’, an American, soft, white, pastry-type wheat released in 1974 and known for its amenability to Agrobacterium tumefaciens-mediated transformation and genome editing. Accurate, long-read sequences were obtained using PacBio circular consensus sequencing with the HiFi approach. Sequence reads from 16 SMRT cells assembled using the hifiasm assembler produced assemblies with N50 greater than 20 Mb. We used the Omni-C chromosome conformation capture technique to order contigs into chromosome-level assemblies, resulting in 21 pseudomolecules with a cumulative size of 14.7 and 0.3 Gb of unanchored contigs. Mapping of published short reads from a transgenic wheat plant with an edited seed-dormancy gene, TaQsd1, identified four positions of transgene insertion into wheat chromosomes. Detection of guide RNA sequences in pseudomolecules provided candidates for off-target mutation induction. These results demonstrate the efficiency of chromosome-scale assembly using PacBio HiFi reads and their application in wheat genome-editing studies.     

基于短序列测序数据的四倍体拟南芥转录组研究

为了促进对四倍体拟南芥(A.suecica)的研究,阐明多倍体植物在染色体加倍过程中遗传物质的变化,从而在分子层面上解释多倍体植物的环境适应和进化机制,描述了一套基于第二代测序技术的转录组短序列组装和生物信息学分析方法.通过对23 000 000条来至于Illumina测序平台的序列数据进行SOAPdenovo组装,以...     

Directed sequencing and annotation of three Dicentrarchus labrax L. chromosomes by applying Sanger- and pyrosequencing technologies on pooled DNA of comparatively mapped BAC clones

Dicentrarchus labrax is one of the major marine aquaculture species in the European Union. In this study, we have developed a directed-sequencing strategy to sequence three sea bass chromosomes and compared results with other teleosts.Three BAC DNA pools were created from sea bass BAC clones that mapped to stickleback chromosomes/groups V, XVII and XXI. The pools were sequenced to 17-39x coverage by pyrosequencing. Data assembly was supported by Sanger reads and mate pair data and resulted in superscaffolds of 13.2 Mb, 17.5 Mb and 13.7 Mb respectively. Annotation features of the superscaffolds include 1477 genes. We analyzed size change of exon, intron and intergenic sequence between teleost species and deduced a simple model for the evolution of genome composition in teleost lineage.Combination of second generation sequencing technologies, Sanger sequencing and genome partitioning strategies allows “high-quality draft assemblies” of chromosome-sized superscaffolds, which are crucial for the prediction and annotation of complete genes.