Biology subjects

Player, R. A.

Publications and source records attributed to Player, R. A..

2 recordsLinked to original sources

bioRxiv2020

A Phased Canis lupus familiaris Labrador Retriever Reference Genome Utilizing High Molecular Weight DNA Extraction Methods and High Resolution Sequencing Technologies

Reference genome fidelity is critically important for genome wide association studies (GWAS), yet many are incomplete or too dissimilar from the study population. A typical whole genome sequencing approach implies short-read technologies resulting in fragmented assemblies with regions of ambiguity low complexity. Further information is lost by economic necessity when genotyping populations, as lower resolution technologies such as genotyping arrays are commonly utilized. Here we present a phased reference genome for Canis lupus familiaris utilizing high molecular weight sequencing technologies. We tested wet lab and bioinformatic approaches to demonstrate a minimum workflow to generate the 2.4 gigabase genome for a Labrador Retriever. The resulting de novo assembly required eight Oxford Nanopore R9.4 flowcells (~23X depth) and running a 10X Genomics library on the equivalent of one lane of an Illumina NovaSeq S1 flowcell (~88X depth), bringing the cost of generating a nearly complete reference genome to less than $10K. Mapping of publicly available short-read data from ten Labrador Retrievers against this breed-specific reference resulted in an average of approximately 1% more aligned reads compared to mapping against the current gold standard reference (CanFam3.1, p<0.001), indicating a more complete breed-specific reference. An average 15% reduction of variant calls was observed from the same mapped data, which increases the chance of identifying low effect size variants in a GWAS. We believe that by incorporating the cost to produce a full genome assembly into any large-scale canine genotyping study, an investigator can make an informed cost/benefit analysis regarding genotyping technology.

genomics↗

bioRxiv2020

Reference genome for the highly transformable Setaria viridis cultivar ME034V

Setaria viridis (green foxtail) is an important model system for improving cereal crops due to its diploid genome, ease of cultivation, and use of C4 photosynthesis. The S. viridis cultivar ME034V is exceptionally transformable, but the lack of a sequenced genome for this cultivar has limited its utility. We present a 397 Mb highly contiguous de novo assembly of ME034V using ultra-long nanopore sequencing technology (read N50=41kb). We estimate that this genome is largely complete based on our updated k-mer based genome size estimate of 401 Mb for S. viridis. Genome annotation identified 37,908 protein-coding genes and >300k repetitive elements comprising 46% of the genome. We compared the ME034V assembly with two other previously sequenced Setaria genomes as well as to a diversity panel of 235 S. viridis cultivars. We found the genome assemblies to be largely syntenic, but numerous unique polymorphic structural variants were discovered. Several ME034V deletions may be associated with recent retrotransposition of copia and gypsy LTR repeat families, as evidenced by their low genotype frequencies in the sampled population. Lastly, we performed a phylogenomic analysis to identify gene families that have expanded in Setaria, including those involved in specialized metabolism and plant defense response. The high continuity of the ME034V genome assembly validates the utility of ultra-long DNA sequencing to improve genetic resources for emerging model organisms. Structural variation present in Setaria illustrates the importance of obtaining the proper genome reference for genetic experiments. Thus, we anticipate that the ME034V genome will be of significant utility for the Setaria research community.

genomics↗