De Novo Transcriptome Assembly and SNP Discovery for the Development of dCAPS Markers in Oat

Cultivated oat (Avena sativa L.) is an important cereal crop that has captured interest worldwide due to its nutritional properties and associated health benefits. Despite this interest, oat has lagged behind other cereal crops in genome studies and the development of DNA markers due to its large and complex genome. RNA-Seq technology has been widely used for transcriptome analysis, functional gene study, and DNA marker development. In this study, we performed the transcriptome sequencing of 10 oat varieties at the seedling stage using the Illumina platform for the development of DNA markers. In total, 31,187,392~41,304,176 trimmed reads (an average of 34,322,925) were generated from 10 oat varieties. All of the trimmed reads of these varieties were assembled and generated, yielding a total of 128,244 assembled unigenes with an average length of 1071.7 bp and N50 of 1752 bp. According to gene ontology (GO) analysis, 30.7% of unigenes were assigned to the “catalytic activity” of the parent term in the molecular function category. Of the 1273 dCAPS markers developed using 491 genotype-specific SNPs, 30 markers exhibiting polymorphism in 28 oat varieties were finally selected. The transcriptome data of oat varieties could be used for functional studies about the seedling stage of oat and information about sequence variations in DNA marker development. These 30 dCAPS markers will be utilized for oat genetic analysis, cultivar identification, and breeders’ rights protection.

Genome-Wide DNA Polymorphism Analysis and Molecular Marker Development for the Setaria italica Variety “SSR41” and Positional Cloning of the Setaria White Leaf Sheath Gene SiWLS1

Genome-wide DNA polymorphism analysis and molecular marker development are important for forward genetics research and DNA marker-assisted breeding. As an ideal model system for Panicoideae grasses and an important minor crop in East Asia, foxtail millet (Setaria italica) has a high-quality reference genome as well as large mutant libraries based on the “Yugu1” variety. However, there is still a lack of genetic and mutation mapping tools available for forward genetics research on S. italica. Here, we screened another S. italica genotype, “SSR41”, which is morphologically similar to, and readily cross-pollinates with, “Yugu1”. High-throughput resequencing of “SSR41” identified 1,102,064 reliable single nucleotide polymorphisms (SNPs) and 196,782 insertions/deletions (InDels) between the two genotypes, indicating that these two genotypes have high genetic diversity. Of the 8,361 high-quality InDels longer than 20 bp that were developed as molecular markers, 180 were validated with 91.5% accuracy. We used “SSR41” and these developed molecular markers to map the white leaf sheath gene SiWLS1. Further analyses showed that SiWLS1 encodes a chloroplast-localized protein that is involved in the regulation of chloroplast development in bundle sheath cells in the leaf sheath in S. italica and is related to sensitivity to heavy metals. Our study provides the methodology and an important resource for forward genetics research on Setaria.

Whole genome survey and microsatellite motif identification ofArtemia franciscana

Artemia is an industrially important genus used in aquaculture as a nutritious diet for fish and as an aquatic model organism for toxicity tests. However, despite the significance of Artemia, genomic research remains incomplete and knowledge on its genomic characteristics is insufficient. In particular, Artemia franciscana of North America has been widely used in fisheries of other continents, resulting in invasion of native species. Therefore, studies on population genetics and molecular marker development as well as morphological analyses are required to investigate its population structure and to discriminate closely related species. Here, we used the Illumina Hi-Seq platform to estimate the genomic characteristics of A. franciscana through genome survey sequencing (GSS). Further, simple sequence repeat (SSR) loci were identified for microsatellite marker development. The predicted genome size was ∼867 Mb using K-mer (a sequence of k characters in a string) analysis (K = 17), and heterozygosity and duplication rates were 0.655 and 0.809%, respectively. A total of 421467 SSRs were identified from the genome survey assembly, most of which were dinucleotide motifs with a frequency of 77.22%. The present study will be a useful basis in genomic and genetic research for A. franciscana.