DNA Research: An International Journal for Rapid Publication of Reports on Genes and Genomes最新文献

Spinach (Spinacia oleracea) is grown as a nutritious leafy vegetable worldwide. To accelerate spinach breeding efficiency, a high-quality reference genome sequence with great completeness and continuity is needed as a basic infrastructure. Here, we used long-read and linked-read technologies to construct a de novo spinach genome assembly, designated SOL_r1.1, which was comprised of 287 scaffolds (total size: 935.7 Mb; N50 = 11.3 Mb) with a low proportion of undetermined nucleotides (Ns = 0.34%) and with high gene completeness (BUSCO complete 96.9%). A genome-wide survey of resistance gene analogues identified 695 genes encoding nucleotide-binding site domains, receptor-like protein kinases, receptor-like proteins and transmembrane-coiled coil domains. Based on a high-density double-digest restriction-site associated DNA sequencing-based linkage map, the genome assembly was anchored to six pseudomolecules representing ∼73.5% of the whole genome assembly. In addition, we used SOL_r1.1 to identify quantitative trait loci for bolting timing and fruit/seed shape, which harbour biologically plausible candidate genes, such as homologues of the FLOWERING LOCUS T and EPIDERMAL PATTERNING FACTOR-LIKE genes. The new genome assembly, SOL_r1.1, will serve as a useful resource for identifying loci associated with important agronomic traits and for developing molecular markers for spinach breeding/selection programs.

The Tibetan Schizothoracinae fish Gymnocypris przewalskii has the ability to adapt to the extreme plateau environment, making it an ideal biological material for evolutionary biology research. However, the lack of well-annotated reference genomes has limited the study of the molecular genetics of G. przewalskii. To characterize its transcriptome features, we first used long-read sequencing technology in combination with RNA-seq for transcriptomic analysis. A total of 159,053 full-length (FL) transcripts were captured by Iso-Seq, having a mean length of 3,445 bp with N50 value of 4,348. Of all FL transcripts, 145,169 were well-annotated in the public database and 134,537 contained complete open reading frames. There were 4,149 pairs of alternative splicing events, of which three randomly selected were defined by RT-PCR and sequencing, and 13,293 long non-coding RNAs detected, based on all-vs.-all BLAST. A total of 118,185 perfect simple sequence repeats were identified from FL transcripts. The FL transcriptome might provide basis for further research of G. przewalskii.

The Echinodermata is characterized by a secondarily evolved pentameral body plan. While the evolutionary origin of this body plan has been the subject of debate, the molecular mechanisms underlying its development are poorly understood. We assembled a de novo developmental transcriptome from the embryo through metamorphosis in the sea star Parvulastra exigua. We use the asteroid model as it represents the basal-type echinoderm body architecture. Global variation in gene expression distinguished the gastrula profile and showed that metamorphic and juvenile stages were more similar to each other than to the pre-metamorphic stages, pointing to the marked changes that occur during metamorphosis. Differential expression and gene ontology (GO) analyses revealed dynamic changes in gene expression throughout development and the transition to pentamery. Many GO terms enriched during late metamorphosis were related to neurogenesis and signalling. Neural transcription factor genes exhibited clusters with distinct expression patterns. A suite of these genes was up-regulated during metamorphosis (e.g. Pax6, Eya, Hey, NeuroD, FoxD, Mbx, and Otp). In situ hybridization showed expression of neural genes in the CNS and sensory structures. Our results provide a foundation to understand the metamorphic transition in echinoderms and the genes involved in development and evolution of pentamery.

Radish (Raphanus sativus L.) is cultivated around the world as a vegetable crop and exhibits diverse morphological and physiological features. DNA polymorphisms are responsible for differences in traits among cultivars. In this study, we determined genome-wide single-nucleotide polymorphisms (SNPs) among geographically diverse radish accessions using the double-digest restriction site-associated DNA sequencing (ddRAD-Seq) method. A total of 52,559 SNPs was identified in a collection of over 500 radish accessions (cultivated and wild) from East Asia, South and Southeast Asia, and the Occident and Near East. In addition, 2,624 SNP sites without missing data (referred to as common SNP sites) were identified among 510 accessions. Genetic diversity analyses, based on the common SNP sites, divided the cultivated radish accessions into four main groups, each derived from four geographical areas (Japan, East Asia, South and Southeast Asia, and the Occident and Near East). Furthermore, we discuss the origin of cultivated radish and its migration from the West to East Asia. SNP data generated in this work will facilitate further genetic studies on the radish breeding and production of DNA markers.

Short interspersed nuclear elements (SINEs) are non-autonomous retrotransposons that are highly abundant, but not well annotated, in plant genomes. In this study, we identified 41,573 copies of SINEs in seven citrus genomes, including 11,275 full-length copies. The citrus SINEs were distributed among 12 families, with an average full-length rate of 0.27, and were dispersed throughout the chromosomes, preferentially in AT-rich areas. Approximately 18.4% of citrus SINEs were found in close proximity (≤1 kb upstream) to genes, indicating a significant enrichment of SINEs in promoter regions. Citrus SINEs promote gene and genome evolution by offering exons as well as splice sites and start and stop codons, creating novel genes and forming tandem and dispersed repeat structures. Comparative analysis of unique homologous SINE-containing loci (HSCLs) revealed chromosome rearrangements in sweet orange, pummelo, and mandarin, suggesting that unique HSCLs might be valuable for understanding chromosomal abnormalities. This study of SINEs provides us with new perspectives and new avenues by which to understand the evolution of citrus genes and genomes.