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July 7, 2019

Multiple hybrid de novo genome assembly of finger millet, an orphan allotetraploid crop.

Finger millet (Eleusine coracana (L.) Gaertn) is an important crop for food security because of its tolerance to drought, which is expected to be exacerbated by global climate changes. Nevertheless, it is often classified as an orphan/underutilized crop because of the paucity of scientific attention. Among several small millets, finger millet is considered as an excellent source of essential nutrient elements, such as iron and zinc; hence, it has potential as an alternate coarse cereal. However, high-quality genome sequence data of finger millet are currently not available. One of the major problems encountered in the genome assembly of this species was its polyploidy, which hampers genome assembly compared with a diploid genome. To overcome this problem, we sequenced its genome using diverse technologies with sufficient coverage and assembled it via a novel multiple hybrid assembly workflow that combines next-generation with single-molecule sequencing, followed by whole-genome optical mapping using the Bionano Irys® system. The total number of scaffolds was 1,897 with an N50 length?>2.6?Mb and detection of 96% of the universal single-copy orthologs. The majority of the homeologs were assembled separately. This indicates that the proposed workflow is applicable to the assembly of other allotetraploid genomes.© The Author 2017. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.


July 7, 2019

Is sex irreplaceable? Towards the molecular regulation of apomixis

Apomixis, defined as the asexual plant reproduction through seeds that results in the production of genetically uniform progeny and a natural way of cloning. Currently there are more than 400 plant species known to use apomixis as a strategy for their propagation. The primary fundamental aspects of apomixis are the bypassing of meiosis and parthenogenetic development of the embryo without fertilization. Apomixis attracts special attention because of its potential value for agriculture, as it could be harnessed for plant breeding programs enabling the permanent fixation of heterosis in crop plants. A better understanding of the molecular and genetic regulation of apomixis is important for developmental and evolutionary perspectives but also for implementation of engineering of apomixis traits into agricultural crop plants. Despite apomixis is considered as one of the key technologies for the improving agriculture, but currently how genetic and molecular regulation of this important trait occurs is not fully known. Recent information on the biology of apomixis and genes and genetic loci associated with the regulation of different components of apomixis is provided in the present review.


July 7, 2019

Genome sequences for multiple Clavibacter strains from different subspecies.

The Gram-positive genus Clavibacter harbors economically important plant pathogens infecting a variety of agricultural crops, such as potato, tomato, corn, barley, etc. Here, we report five new genome sequences, those of strains CFIA-Cs3N, CFIA-CsR14, LMG 3663(T), LMG 7333(T), and ATCC 33566(T), from different subspecies of Clavibacter michiganensis All these genomic data will be used for reclassification and niche-adapted feature comparisons.© Crown copyright 2017.


July 7, 2019

Evolution of sphingomonad gene clusters related to pesticide catabolism revealed by genome sequence and mobilomics of Sphingobium herbicidovorans MH.

Bacterial degraders of chlorophenoxy herbicides have been isolated from various ecosystems, including pristine environments. Among these degraders, the sphingomonads constitute a prominent group that displays versatile xenobiotic-degradation capabilities. Four separate sequencing strategies were required to provide the complete sequence of the complex and plastic genome of the canonical chlorophenoxy herbicide-degrading Sphingobium herbicidovorans MH. The genome has an intricate organization of the chlorophenoxy-herbicide catabolic genes sdpA, rdpA, and cadABCD that encode the (R)- and (S)-enantiomer-specific 2,4-dichlorophenoxypropionate dioxygenases and four subunits of a Rieske non-heme iron oxygenase involved in 2-methyl-chlorophenoxyacetic acid degradation, respectively. Several major genomic rearrangements are proposed to help understand the evolution and mobility of these important genes and their genetic context. Single-strain mobilomic sequence analysis uncovered plasmids and insertion sequence-associated circular intermediates in this environmentally important bacterium and enabled the description of evolutionary models for pesticide degradation in strain MH and related organisms. The mobilome presented a complex mosaic of mobile genetic elements including four plasmids and several circular intermediate DNA molecules of insertion-sequence elements and transposons that are central to the evolution of xenobiotics degradation. Furthermore, two individual chromosomally integrated prophages were shown to excise and form free circular DNA molecules. This approach holds great potential for improving the understanding of genome plasticity, evolution, and microbial ecology.© The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.


July 7, 2019

A high-quality genome assembly of quinoa provides insights into the molecular basis of salt bladder-based salinity tolerance and the exceptional nutritional value.

Chenopodium quinoa is a halophytic pseudocereal crop that is being cultivated in an ever-growing number of countries. Because quinoa is highly resistant to multiple abiotic stresses and its seed has a better nutritional value than any other major cereals, it is regarded as a future crop to ensure global food security. We generated a high-quality genome draft using an inbred line of the quinoa cultivar Real. The quinoa genome experienced one recent genome duplication about 4.3 million years ago, likely reflecting the genome fusion of two Chenopodium parents, in addition to the ? paleohexaploidization reported for most eudicots. The genome is highly repetitive (64.5% repeat content) and contains 54 438 protein-coding genes and 192 microRNA genes, with more than 99.3% having orthologous genes from glycophylic species. Stress tolerance in quinoa is associated with the expansion of genes involved in ion and nutrient transport, ABA homeostasis and signaling, and enhanced basal-level ABA responses. Epidermal salt bladder cells exhibit similar characteristics as trichomes, with a significantly higher expression of genes related to energy import and ABA biosynthesis compared with the leaf lamina. The quinoa genome sequence provides insights into its exceptional nutritional value and the evolution of halophytes, enabling the identification of genes involved in salinity tolerance, and providing the basis for molecular breeding in quinoa.


July 7, 2019

Echinochloa crus-galli genome analysis provides insight into its adaptation and invasiveness as a weed.

Barnyardgrass (Echinochloa crus-galli) is a pernicious weed in agricultural fields worldwide. The molecular mechanisms underlying its success in the absence of human intervention are presently unknown. Here we report a draft genome sequence of the hexaploid species E. crus-galli, i.e., a 1.27?Gb assembly representing 90.7% of the predicted genome size. An extremely large repertoire of genes encoding cytochrome P450 monooxygenases and glutathione S-transferases associated with detoxification are found. Two gene clusters involved in the biosynthesis of an allelochemical 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and a phytoalexin momilactone A are found in the E. crus-galli genome, respectively. The allelochemical DIMBOA gene cluster is activated in response to co-cultivation with rice, while the phytoalexin momilactone A gene cluster specifically to infection by pathogenic Pyricularia oryzae. Our results provide a new understanding of the molecular mechanisms underlying the extreme adaptation of the weed.


July 7, 2019

Complete circular genome sequence and temperature independent adaptation to anaerobiosis of Listeria weihenstephanensis DSM 24698.

The aim of this study was to analyze the adaptation of the environmental Listeria weihenstephanensis DSM 24698 to anaerobiosis. The complete circular genome sequence of this species is reported and the adaptation of L. weihenstephanensis DSM 24698 to oxygen availability was investigated by global transcriptional analyses via RNAseq at 18 and 34°C. A list of operons was created based on the transcriptional data. Forty-two genes were upregulated anaerobically and 62 genes were downregulated anaerobically. The oxygen dependent gene expression of selected genes was further validated via qPCR. Many of the differentially regulated genes encode metabolic enzymes indicating broad metabolic adaptations with respect to oxygen availability. Genes showing the strongest oxygen-dependent adaption encoded nitrate (narGHJI) and nitrite (nirBD) reductases. Together with the observation that nitrate supported anaerobic growth, these data indicate that L. weihenstephanensis DSM 24698 performs anaerobic nitrate respiration. The wide overlap between the oxygen-dependent transcriptional regulation at 18 and 34°C suggest that temperature does not play a key role in the oxygen-dependent transcriptional regulation of L. weihenstephanensis DSM 24698.


July 7, 2019

Complete genome sequence of Bacillus velezensis GQJK49, a plant growth-promoting rhizobacterium with antifungal activity.

Bacillus velezensis GQJK49 is a plant growth-promoting rhizobacterium with antifungal activity, which was isolated from Lycium barbarum L. rhizosphere. Here, we report the complete genome sequence of B. velezensis GQJK49. Twelve gene clusters related to its biosynthesis of secondary metabolites, including antifungal and antibacterial antibiotics, were predicted. Copyright © 2017 Ma et al.


July 7, 2019

Complete genome sequence of Mesorhizobium ciceri bv. biserrulae WSM1497, an efficient nitrogen-fixing microsymbiont of the forage legume Biserrula pelecinus.

We report here the complete genome sequence of Mesorhizobium ciceri bv. biserrulae strain WSM1497, the efficient nitrogen-fixing microsymbiont and commercial inoculant in Australia of the forage legume Biserrula pelecinus The genome consists of 7.2 Mb distributed across a single chromosome (6.67 Mb) and a single plasmid (0.53 Mb). Copyright © 2017 Brewer et al.


July 7, 2019

Whole-genome sequence of Chlamydia abortus strain GN6 isolated from aborted yak fetus.

The obligate intracellular Gram-negative bacterium Chlamydia abortus is one of the causative agents of abortion and fetal loss in sheep, goats, and cattle in many countries. It also affects the reproductivity of yaks (Bos grunniens). This study reports the whole-genome sequence of Chlamydia abortus strain GN6, which was isolated from aborted yak fetus in Qinghai-Tibetan Plateau, China. Copyright © 2017 Li et al.


July 7, 2019

Complete genome analysis of Lactobacillus fermentum SK152 from kimchi reveals genes associated with its antimicrobial activity.

Research findings on probiotics highlight their importance in repressing harmful bacteria, leading to more extensive research on their potential applications. We analysed the genome of Lactobacillus fermentum SK152, which was isolated from the Korean traditional fermented vegetable dish kimchi, to determine the genetic makeup and genetic factors responsible for the antimicrobial activity of L. fermentum SK152 and performed a comparative genome analysis with other L. fermentum strains. The genome of L. fermentum SK152 was found to comprise a complete circular chromosome of 2092 273 bp, with an estimated GC content of 51.9% and 2184 open reading frames. It consisted of 2038 protein-coding genes and 73 RNA-coding genes. Moreover, a gene encoding a putative endolysin was found. A comparative genome analysis with other L. fermentum strains showed that SK152 is closely related to L. fermentum 3872 and F-6. An evolutionary analysis identified five positively selected genes that encode proteins associated with transport, survival and stress resistance. These positively selected genes may be essential for L. fermentum to colonise and survive in the stringent environment of the human gut and exert its beneficial effects. Our findings highlight the potential benefits of SK152.© FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

The Tartary buckwheat genome provides insights into rutin biosynthesis and abiotic stress tolerance.

Tartary buckwheat (Fagopyrum tataricum) is an important pseudocereal crop that is strongly adapted to growth in adverse environments. Its gluten-free grain contains complete proteins with a well-balanced composition of essential amino acids and is a rich source of beneficial phytochemicals that provide significant health benefits. Here, we report a high-quality, chromosome-scale Tartary buckwheat genome sequence of 489.3 Mb that is assembled by combining whole-genome shotgun sequencing of both Illumina short reads and single-molecule real-time long reads, sequence tags of a large DNA insert fosmid library, Hi-C sequencing data, and BioNano genome maps. We annotated 33 366 high-confidence protein-coding genes based on expression evidence. Comparisons of the intra-genome with the sugar beet genome revealed an independent whole-genome duplication that occurred in the buckwheat lineage after they diverged from the common ancestor, which was not shared with rosids or asterids. The reference genome facilitated the identification of many new genes predicted to be involved in rutin biosynthesis and regulation, aluminum stress resistance, and in drought and cold stress responses. Our data suggest that Tartary buckwheat’s ability to tolerate high levels of abiotic stress is attributed to the expansion of several gene families involved in signal transduction, gene regulation, and membrane transport. The availability of these genomic resources will facilitate the discovery of agronomically and nutritionally important genes and genetic improvement of Tartary buckwheat. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.


July 7, 2019

Complete genome sequence of endophyte Bacillus flexus KLBMP 4941 reveals its plant growth promotion mechanism and genetic basis for salt tolerance.

Bacillus flexus KLBMP 4941 is a halotolerant endophyte isolated from the halophyte Limonium sinense. This strain can improve host seedling growth under salt stress conditions. We here report the complete genome information of endophyte KLBMP 4941. It has a circular chromosome and two plasmids for a total genome 4,104,242 bp in size with a G+C content of 38.09%. Genes related to plant growth promotion (PGP), such as those associated with nitrogen fixation, siderophore, spermidine, and acetoin synthesis were found in the KLBMP 4941 genome. Some genes responsible for high salinity tolerance, like genes associated with the Na(+)/H(+) antiporter, glycine betaine transporter, and betaine-aldehyde dehydrogenase were also found in the KLBMP 4941 genome. The genome analysis will provide better understanding of the mechanisms underlying the promotion of plant growth in strain KLBMP 4941 under salt stress conditions and its ability to adapt to coastal salt marsh habitats, and provide a basis for its further biotechnological applications in agriculture. Copyright © 2017 Elsevier B.V. All rights reserved.


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