Dracaena marginata is a widely cultivated horticultural plant in the world, which has high ornamental and medicinal value. In this study, the whole genome of leaves from D. marginata was sequenced by Illumina HiSeq 4000 platform. The chloroplast genome were assembled for functional annotation, sequence characteristics and phylogenetic analysis. The results showed that the chloroplast genome of D. marginata composed of four regions with a size of 154 926 bp, which was the smallest chloroplast genome reported for Dracaena species to date. A total of 132 genes were identified, including 86 coding genes, 38 tRNA genes and 8 rRNA genes. Codon bias analysis found that the codon usage bias was weak and there was a bias for using A/U base endings. 46 simple sequence repeat and 54 repeats loci were detected in the chloroplast genome, with the maximum detection rate in the large single copy region and inverted repeat region, respectively. The inverted repeats boundaries of D. marginata and Dracaena were highly conserved, whereas gene location differences occurred. Phylogenetic analysis revealed that D. serrulata and D. cinnabari form a monophyletic clade, which was the closest relationship and conformed to the morphological classification characteristics. The analysis of the chloroplast genome of D. marginata provides important data basis for species identification, genetic diversity and chloroplast genome engineering of Dracaena.
Phylogeny ; Dracaena ; Genome, Chloroplast/genetics* ; Base Sequence ; Genes, Plant

The aquatic ferns of the genus Azolla are nitrogen-fixing plants that have great potentials in agricultural production and environmental conservation. Azolla in many aspects is qualified to serve as a model organism for genomic studies because of its importance in agriculture, its unique position in plant evolution, its symbiotic relationship with the N2-fixing cyanobacterium, Anabaena azollae, and its moderate-sized genome. The goals of this genome project are not only to understand the biology of the Azolla genome to promote its applications in biological research and agriculture practice but also to gain critical insights about evolution of plant genomes. Together with the strategic and technical improvement as well as cost reduction of DNA sequencing, the deciphering of their genetic code is imminent.
Cyanobacteria ; genetics ; Ferns ; Genes, Plant ; Genome, Plant ; Genomics ; methods ; Nitrogen ; metabolism ; Plants ; genetics ; Sequence Analysis, DNA

Chloroplast genome sequences have comprehensive application prospects in DNA barcoding and chloroplast engineering in traditional Chinese medicine. The complete chloroplast genome of Magnolia officinalis sequenced by high-throughput pyrosequencing and a sequencing procedure was established. Fourteen contigs were obtained after de nove assembly. The sequencing percent of coverage was 99.99%. The chloroplast genome is 160 183 bp in size, and has a typical quadripartite structure with the large (LSC, 88 210 bp) and small copy (SSC, 18 843 bp) regions separated by two copies of an inverted repeat (IRs, 26 565 bp each). chloroplast genes were successfully annotated, of which 17 genes located in each IR region. The chloroplast genome features in Magnolia officinalis are nearly identical to those from other Magnoliid chloroplast genomes. Phylogenetic analyses were performed based on 81 shared coding-genes for a total of 9 Magnolia samples of 5 closely related species. Results showed that distinguishing among species was generally straightforward at the species and population level. This study confirmed the effectiveness of our chloroplast genome sequencing procedure. The chloroplast genome can provide distinguishing differences to help identify Magnolia officinalis and its closely related plants.
Base Sequence ; Chloroplasts ; genetics ; DNA, Chloroplast ; genetics ; Genes, Chloroplast ; Genes, Plant ; Genome, Chloroplast ; Genome, Plant ; High-Throughput Nucleotide Sequencing ; Magnolia ; classification ; genetics ; Phylogeny ; Sequence Analysis, DNA

Genetic improvement for drought stress tolerance in rice involves the quantitative nature of the trait, which reflects the additive effects of several genetic loci throughout the genome. Yield components and related traits under stressed and well-water conditions were assayed in mapping populations derived from crosses of AzucenaxIR64 and AzucenaxBala. To find the candidate rice genes underlying Quantitative Trait Loci (QTL) in these populations, we conducted in silico analysis of a candidate region flanked by the genetic markers RM212 and RM319 on chromosome 1, proximal to the semi-dwarf (sd1) locus. A total of 175 annotated genes were identified from this region. These included 48 genes annotated by functional homology to known genes, 23 pseudogenes, 24 ab initio predicted genes supported by an alignment match to an EST (Expressed sequence tag) of unknown function, and 80 hypothetical genes predicted solely by ab initio means. Among these, 16 candidate genes could potentially be involved in drought stress response.
Disasters ; Expressed Sequence Tags ; Gene Expression Regulation, Plant ; genetics ; Gene Library ; Genes, Plant ; genetics ; Genome, Plant ; Oryza ; genetics ; Physical Chromosome Mapping ; Plant Diseases ; genetics ; Quantitative Trait Loci ; genetics ; Signal Transduction ; Water ; metabolism

We report the recovery of a 7068-nt viral sequence from the "viral fossils" embedded in the genome of Alhagi sparsifolia, a typical desert plant. Although the full viral genome remains to be completed, the putative genome structure, the deduced amino acids and phylogenetic analysis unambiguously demonstrate that this viral sequence represents a novel species of the genus Badnavirus. The putative virus is tentatively termed Alhagi bacilliform virus (ABV). Southern blotting and inverse polymerase chain reaction (PCR) data indicate that the ABV-related sequence is integrated into the A. sparsifolia genome, and probably does not give rise to functional episomal virus. Molecular evidence that the ABV sequence exists widely in A. sparsifolia is also presented. To our knowledge, this is the first endogenous badnavirus identified from plants in the Gobi desert, and may provide new clues on the evolution, geographical distribution as well as the host range of the badnaviruses.
Badnavirus/genetics* ; Biological Evolution ; Desert Climate ; Fabaceae/virology* ; Genes, Plant ; Genetic Variation ; Genome, Viral ; Geography ; Open Reading Frames ; Phylogeny ; Plant Diseases/virology* ; Plasmids ; Sequence Analysis, RNA

Intron prediction is an important problem of the constantly updated genome annotation. Using two model plant (rice and Arabidopsis) genomes, we compared two well-known intron prediction tools: the Blast-Like Alignment Tool (BLAT) and Sim4cc. The results showed that each of the tools had its own advantages and disadvantages. BLAT predicted more than 99% introns of whole genomic introns with a small number of false-positive introns. Sim4cc was successful at finding the correct introns with a false-negative rate of 1.02% to 4.85%, and it needed a longer run time than BLAT. Further, we evaluated the intron information of 10 complete plant genomes. As non-coding sequences, intron lengths are not limited by a triplet codon frame; so, intron lengths have three phases: a multiple of three bases (3n), a multiple of three bases plus one (3n + 1), and a multiple of three bases plus two (3n + 2). It was widely accepted that the percentages of the 3n, 3n + 1, and 3n + 2 introns were quite similar in genomes. Our studies showed that 80% (8/10) of species were similar in terms of the number of three phases. The percentages of 3n introns in Ostreococcus lucimarinus was excessive (47.7%), while in Ostreococcus tauri, it was deficient (29.1%). This discrepancy could have been the result of errors in intron prediction. It is suggested that a three-phase evaluation is a fast and effective method of detecting intron annotation problems.
Codon ; Genome ; Genome, Plant ; Humans ; Introns ; Plants ; Triplets

Malus floribunda Siebold. (Malus) is widely cultivated all over the world, which is of high ornamental value and breeding significance. Comparative analysis of the chloroplast genome can help enrich the phylogenetic relationship and facilitate germplasm utilization of Malus. Based on the whole genome sequencing data, a complete chloroplast genome (M. floribunda) with tetrad structure was assembled. The chloroplast genome (160 037 bp) was composed of a large single-copy (LSC) region (88 142 bp), inverted repeat (IR) B (26 353 bp), a small single-copy (SSC) region (19 189 bp), and IRA (26 353 bp). A total of 111 genes were annotated: 78 protein-coding genes, 29 tRNA genes and 4 rRNA genes. In addition, a large number of repeat sequences were identified in the genome, which was slightly different from that of M. sieboldii and M. toringoides. As for the relative synonymous codon usage, 30 high-frequency codons were found, and the codons tended to end with A/T. The results of interspecific sequence alignment and boundary analysis suggested the sequence variation of the LSC region was large, and the expansion and contraction of the SC region and IR region of the eight Malus species were generally similar. According to the phylogenetic analysis of chloroplast genome sequences, M. floribunda, M. hupehensis, and M. toringoides were grouped into one clade. The findings in this study can provide data support for the development of genetic markers and utilization of germplasm resources in the future.
Genome, Chloroplast ; Malus ; Phylogeny ; Plant Breeding ; Codon

We developed a novel method for constructing nearly random peptide library. Genomic DNAs extracted from tissue or cells of large genome species were digested with frequent cutter to produce short DNA fragments. These short fragments can be considered nearly random. Nearly random peptide libraries can be constructed by cloning the short fragments into appropriate expression vectors and transformation into host cells. Genomic DNA from one species can be digested with different restriction enzymes and ligated to different reading frames to produce several different libraries. In this study, we digested tobacco genomic DNA with two enzymes and cloned into three different reading frames to make totally six nearly random peptide libraries.
DNA, Plant ; genetics ; Genome, Plant ; genetics ; Peptide Library ; Tobacco ; genetics

DNA methylation is an important type of epigenetic modification in eukaryotes. In order to research genome-wide methylation levels and patterns in foxtail millet (Setaria italica), the Methylation Sensitive Amplified Polymorphism (MSAP) analysis (employing double digestion with EcoR I and Hpa II/Msp I) was established and applied in two foxtail millet cultivars (Chaogu 58 and Yugu 1). The results showed that 32 pairs of MSAP primers were selected from 100 MSAP primers, and 1 615 and 1 482 clearly distinguishable and reproducible bands were amplified from Chaogu 58 and Yugu 1 respectively, including 3 types of methylation patterns. Cytosine methylation levels of CCGG context in Chaogu 58 and Yugu 1 were characterized as 6.93% and 8.77% respectively. Such different genomic DNA methylation levels between two foxtail millet varieties may provide a preliminary reference for the cultivation of this crop from a novel epigenetic viewpoint.
DNA Methylation ; Genome, Plant ; Genomics ; Polymorphism, Genetic ; Setaria Plant

Scutellaria baicalensis (S. baicalensis) and Scutellaria barbata (S. barbata) are common medicinal plants of the Lamiaceae family. Both produce specific flavonoid compounds, including baicalein, scutellarein, norwogonin, and wogonin, as well as their glycosides, which exhibit antioxidant and antitumor activities. Here, we report chromosome-level genome assemblies of S. baicalensis and S. barbata with quantitative chromosomal variation (2n = 18 and 2n = 26, respectively). The divergence of S. baicalensis and S. barbata occurred far earlier than previously reported, and a whole-genome duplication (WGD) event was identified. The insertion of long terminal repeat elements after speciation might be responsible for the observed chromosomal expansion and rearrangement. Comparative genome analysis of the congeneric species revealed the species-specific evolution of chrysin and apigenin biosynthetic genes, such as the S. baicalensis-specific tandem duplication of genes encoding phenylalanine ammonia lyase and chalcone synthase, and the S. barbata-specific duplication of genes encoding 4-CoA ligase. In addition, the paralogous duplication, colinearity, and expression diversity of CYP82D subfamily members revealed the functional divergence of genes encoding flavone hydroxylase between S. baicalensis and S. barbata. Analyzing these Scutellaria genomes reveals the common and species-specific evolution of flavone biosynthetic genes. Thus, these findings would facilitate the development of molecular breeding and studies of biosynthesis and regulation of bioactive compounds.
Evolution, Molecular ; Flavonoids/biosynthesis* ; Genome, Plant ; Plant Extracts/genetics* ; Scutellaria/metabolism* ; Whole Genome Sequencing