Identification of a novel glycoside hydrolase family 8 xylanase from Deinococcus geothermalis and its application at low temperatures.

Xylanase is the most important hydrolase in the xylan hydrolase system, the main function of which is ß-1,4-endo-xylanase, which randomly cleaves xylans to xylo-oligosaccharides and xylose. Xylanase has wide ranging of applications, but there remains little research on the cold-adapted enzymes required in some low-temperature industries. Glycoside hydrolase family 8 (GH8) xylanases have been reported to have cold-adapted enzyme activity. In this study, the xylanase gene dgeoxyn was excavated from Deinococcus geothermalis through sequence alignment. The recombinant xylanase DgeoXyn encodes 403 amino acids with a theoretical molecular weight of 45.39 kDa. Structural analysis showed that DgeoXyn has a (α/α)6-barrel fold structure typical of GH8 xylanase. At the same time, it has strict substrate specificity, is only active against xylan, and its hydrolysis products include xylobiose, xylotrinose, xytetranose, xylenanose, and a small amount of xylose. DgeoXyn is most active at 70 â„ƒ and pH 6.0. It is very stable at 10, 20, and 30 â„ƒ, retaining more than 80% of its maximum enzyme activity. The enzyme activity of DgeoXyn increased by 10% after the addition of Mn2+ and decreased by 80% after the addition of Cu2+. The Km and Vmax of dgeox were 42 mg/ml and 20,000 U/mg, respectively, at a temperature of 70 â„ƒ and pH of 6.0 using 10 mg/ml beechwood xylan as the substrate. This research on DgeoXyn will provide a theoretical basis for the development and application of low-temperature xylanase.

Enhanced enzyme thermostability of a family I.3 lipase LipSR1 by T118A mutation at the calcium-binding site.

OBJECTIVES: The lipase gene lipSR1 isolated from oil-contaminated soil exhibits high hydrolytic activity for short-chain fatty acid substrates. A single calcium ion is required to anchor the lid of LipSR1 in an open conformation by coordination with two aspartate residues and three other residues in the lid. The lid of LipSR1 is anchored by Ca2+, which is coordinated by side-chain carboxyl oxygens of Asp153 and Asp157, carbonyl oxygens of Thr118 and Ser144, and the side chain of Gln120. RESULTS: D157A, D153R, Q120A, S144A, and T118A mutants were produced by site-directed mutagenesis in this study. Analyses of hydrolytic activity and thermostability showed that the properties of D157A, D153R, Q120A, and S144A were almost lost, suggesting that Asp157, Asp153, Gln120, and Ser144 are important residues for LipSR1. However, the catalytic performance of T118A was clearly maintained. Moreover, the thermostability of mutant T118A was higher than that of wild-type LipSR1. CONCLUSIONS: These results indicated that mutation of threonine at position 118 improved the stability of the enzyme at high temperature.

A Novel Glycoside Hydrolase DogH Utilizing Soluble Starch to Maltose Improve Osmotic Tolerance in Deinococcus radiodurans.

Deinococcus radiodurans is a microorganism that can adjust, survive or thrive in hostile conditions and has been described as "the strongest microorganism in the world". The underlying mechanism behind the exceptional resistance of this robust bacterium still remains unclear. Osmotic stress, caused by abiotic stresses such as desiccation, salt stress, high temperatures and freezing, is one of the main stresses suffered by microorganisms, and it is also the basic response pathway by which organisms cope with environmental stress. In this study, a unique trehalose synthesis-related gene, dogH (Deinococcus radiodurans orphan glycosyl hydrolase-like family 10), which encodes a novel glycoside hydrolase, was excavated using a multi-omics combination method. The content accumulation of trehalose and its precursors under hypertonic conditions was quantified by HPLC-MS. Ours results showed that the dogH gene was strongly induced by sorbitol and desiccation stress in D. radiodurans. DogH glycoside hydrolase hydrolyzes α-1,4-glycosidic bonds by releasing maltose from starch in the regulation of soluble sugars, thereby increasing the concentration of TreS (trehalose synthase) pathway precursors and trehalose biomass. The maltose and alginate content in D. radiodurans amounted to 48 µg mg protein-1 and 45 µg mg protein-1, respectively, which were 9 and 28 times higher than those in E. coli, respectively. The accumulation of greater intracellular concentrations of osmoprotectants may be the true reason for the higher osmotic stress tolerance of D. radiodurans.

Genome-wide association study reveals the genetic architecture for calcium accumulation in grains of hexaploid wheat (Triticum aestivum L.).

BACKGROUND: Hexaploid wheat (Triticum aestivum L.) is a leading cereal crop worldwide. Understanding the mechanism of calcium (Ca) accumulation in wheat is important to reduce the risk of human micronutrient deficiencies. However, the mechanisms of Ca accumulation in wheat grain are only partly understood. RESULTS: Here, a genome-wide association study (GWAS) was performed to dissect the genetic basis of Ca accumulation in wheat grain using an association population consisting of 207 varieties, with phenotypic data from three locations. In total, 11 non-redundant genetic loci associated with Ca concentration were identified and they explained, on average, 9.61-26.93% of the phenotypic variation. Cultivars containing more superior alleles had increased grain Ca concentrations. Notably, four non-redundant loci were mutually verified by different statistical models in at least two environments, indicating their stability across different environments. Four putative candidate genes linked to Ca accumulation were revealed from the stable genetic loci. Among them, two genes, associated with the stable genetic loci on chromosomes 4A (AX-108912427) and 3B (AX-110922471), encode the subunits of V-type Proton ATPase (TraesCS4A02G428900 and TraesCS3B02G241000), which annotated as the typical generators of a proton gradient that might be involved in Ca homeostasis in wheat grain. CONCLUSION: To identify genetic loci associated with Ca accumulation, we conducted GWAS on Ca concentrations and detected 11 genetic loci; whereas four genetic loci were stable across different environments. A genetic loci hot spot exists at the end of chromosome 4A and associated with the putative candidate gene TraesCS4A02G428900. The candidate gene TraesCS4A02G428900 encodes V-type proton ATPase subunit e and highly expressed in wheat grains, and it possibly involved in Ca accumulation. This study increases our understanding of the genetic architecture of Ca accumulation in wheat grains, which is potentially helpful for wheat Ca biofortification pyramid breeding.

Integrated physiological and transcriptional dissection reveals the core genes involving nutrient transport and osmoregulatory substance biosynthesis in allohexaploid wheat seedlings under salt stress.

BACKGROUND: Soil salinization has become a global problem restricting the seed yield and quality of crops, including wheat (Triticum aestivum L.). Salinity significantly alters plant morphology and severely disrupts physiological homeostasis. Salt tolerance of wheat has been widely studied whereas core ion transporters responsive to salt stress remain elusive. RESULTS: In this study, the wheat seedlings were subjected to salinity toxicity for morpho-physiological and transcriptomic analysis of wheat salt tolerance. There was a inversely proportional relationship between salt concentrations and morpho-physiological parameters. Under the condition of 100 mM NaCl, the H2O2, O2-, MDA content and membrane permeability were significantly increased whereas the chlorophyll content was markedly decreased. Under salt stress, a larger proportion of Na+ was partitioned in the roots than in the shoots, which had a lower Na+/K+ ratio and proline content. Salt stress also obviously affected the homeostasis of other cations. Genome-wide transcriptomic analysis showed that a total of 2,807 and 5,570 differentially expressed genes (DEGs) were identified in the shoots and roots, respectively. Functionality analysis showed that these DEGs were mainly enriched in the KEGG pathways related to carbon metabolism, phenylalanine, and amino acid biosynthesis, and were primarily enriched in the GO terms involving proline metabolism and redox processes. The Na+ transporter genes were upregulated under salt stress, which repressed the gene expression of the K+ transporters. Salt stress also significantly elevated the expression of the genes involved in osmoregulation substances biosynthesis, and obviously affected the expression profiling of other cation transporters. Co-expression network analysis identified TaNHX6-D5/TaNHX4-B7 and TaP5CS2-B3 potentially as core members regulating wheat salt tolerance. CONCLUSIONS: These results might help us fully understand the morpho-physiological and molecular responses of wheat seedlings to salt stress, and provide elite genetic resources for the genetic modification of wheat salt tolerance.

Uncovering the genetic basis of gluten aggregation parameters by genome-wide association analysis in wheat (Triticum aestivum L.) using GlutoPeak.

BACKGROUND: Numerous studies have shown that gluten aggregation properties directly affect the processing quality of wheat, however, the genetic basis of gluten aggregation properties were rarely reported. RESULTS: To explore the genetic basis of gluten aggregation properties in wheat, an association population consisted with 207 wheat genotypes were constructed for evaluating nine parameters of aggregation properties on GlutoPeak across three-year planting seasons. A total of 940 significant SNPs were detected for 9 GlutoPeak parameters through genome-wide association analysis (GWAS). Finally, these SNPs were integrated to 68 non-redundant QTL distributed on 20 chromosomes and 54 QTL was assigned as pleiotropic loci which accounting for multiple parameters of gluten aggregation property. Furthermore, the peak SNPs representing 54 QTL domonstrated additive effect on all the traits. There was a significant positive correlation between the number of favorable alleles and the phenotypic values of each parameter. Peak SNPs of two novel QTL, q3AL.2 and q4DL, which contributing to both PMT (peak maximum time) and A3 (area from the first minimum to torque 15 s before the maximum torque) parameters, were selected for KASP (Kompetitive Allele Specific PCR) markers development and the KASP markers can be used for effectively evaluating the quality of gluten aggregation properties in the association population. CONCLUSION: The rapid and efficient GlutoPeak method for gluten measurement can be used for early selection of wheat breeding. This study revealed the genetic loci related to GlutoPeak parameters in association population, which would be helpful to develop wheat elite lines with improved gluten aggregation through molecular marker-assisted breeding.

Multiomics reveals an essential role of long-distance translocation in regulating plant cadmium resistance and grain accumulation in allohexaploid wheat (Triticum aestivum).

Cadmium (Cd) is a highly toxic heavy metal that readily enters cereals, such as wheat, via the roots and is translocated to the shoots and grains, thereby posing high risks to human health. However, the vast and complex genome of allohexaploid wheat makes it challenging to understand Cd resistance and accumulation. In this study, a Cd-resistant cultivar of wheat, 'ZM1860', and a Cd-sensitive cultivar, 'ZM32', selected from a panel of 442 accessions, exhibited significantly different plant resistance and grain accumulation. We performed an integrated comparative analysis of the morpho-physiological traits, ionomic and phytohormone profiles, genomic variations, transcriptomic landscapes, and gene functionality in order to identify the mechanisms underlying these differences. Under Cd toxicity, 'ZM1860' outperformed 'ZM32', which showed more severe leaf chlorosis, poorer root architecture, higher accumulation of reactive oxygen species, and disordered phytohormone homeostasis. Ionomics showed that 'ZM32' had a higher root-to-shoot translocation coefficient of Cd and accumulated more Cd in the grains than 'ZM1860'. Whole-genome re-sequencing (WGS) and transcriptome sequencing identified numerous DNA variants and differentially expressed genes involved in abiotic stress responses and ion transport between the two genotypes. Combined ionomics, transcriptomics, and functional gene analysis identified the plasma membrane-localized heavy metal ATPase TaHMA2b-7A as a crucial Cd exporter regulating long-distance Cd translocation in wheat. WGS- and PCR-based analysis of sequence polymorphisms revealed a 25-bp InDel site in the promoter region of TaHMA2b-7A, and this was probably responsible for the differential expression. Our multiomics approach thus enabled the identification of a core transporter involved in long-distance Cd translocation in wheat, and it may provide an elite genetic resource for improving plant Cd resistance and reducing grain Cd accumulation in wheat and other cereal crops.

Devosia salina sp. nov., isolated from South China Sea sediment.

An aerobic, Gram-stain-negative, rod-shaped and motile strain, designated SCS-3T, was isolated from deep-sea sediment of the South China Sea. Phylogenetic analysis based on the 16S rRNA gene sequence similarities revealed that strain SCS-3T represented a novel species of the genus Devosia, with closely related strains 'Devosia sediminis' MSA67T (98.61 %), Devosia riboflavina IFO13584T (98.22 %) and Devosia indica IO390501T (97.72 %). The G+C content of the genomic DNA is 63.44 mol%. The digital DNA-DNA hybridization values with 'D. sediminis' MSA67T, D. riboflavina IFO13584T and D. indica IO390501T were 24.50, 21.8 and 24.80 %, respectively. The major polar lipids of strain SCS-3T were diphosphatidylglycerol, phosphatidylglycerol and three unidentified glycolipids. Ubiquinone-10 was the sole isoprenoid quinone, and C16 : 0, C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) were the major fatty acids. Based on polyphasic taxonomic data, strain SCS-3T represents a novel species of the genus Devosia, for which the name Devosia salina sp. nov. is proposed. The type strain is SCS-3T (=JCM 34403T=GDMCC 1.2221T).

Shinella oryzae sp. nov., a novel zearalenone-resistant bacterium isolated from rice paddy soil.

A novel bacterium, designated Z-25 T, was isolated from a rice paddy rhizosphere soil sample from Wuchang County, China. The Z-25 T strain is gram-negative, rod-shaped, non-spore-forming, aerobic, motile by unipolar flagella and straw white in color. A phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain Z-25 belongs to the genus Shinella, and the closest members are Shinella zoogloeoides ATCC 19623 T with 98.58% similarity, S. kummerowiae CCBAU 25,048 T (98.03%) and S. granuli Ch06 T (97.37%). The average nucleotide identity and in silico DNA-DNA hybridization values between strain Z-25 T and the closest members were less than 85.29% and 28.70%, respectively. The predominant fatty acids were the sums of features comprising C18:1 ω7c and/or C18:1 ω6c (34.62%), C18:1 ω7c -11-methyl (20.48%), and C19:0 cyclo ω8c (18.19%). The only respiratory quinone was ubiquinone-10, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Additionally, a genome analysis showed that Z-25 T presented potential functional genes related to the degradation of zearalenone (ZEN). An HPLC analysis indicated that Z-25 T could remove 74.13% of 10 mg/L ZEN after 144 h at 30 °C. Therefore, based on phenotypic, chemotaxonomic, phylogenetic and genotypic analyses, strain Z-25 T represents a novel species in the genus Shinella, for which the name Shinella oryzae sp. nov. is proposed. The type strain is Z-25 T (= GDMCC 1.2424 T = KCTC 82660 T).

Quantitative traits loci mapping and molecular marker development for total glutenin and glutenin fraction contents in wheat.

BACKGROUND: Glutenin contents and compositions are crucial factors influencing the end-use quality of wheat. Although the composition of glutenin fractions is well known, there has been relatively little research on the genetic basis of glutenin fractions in wheat. RESULTS: To elucidate the genetic basis for the contents of glutenin and its fractions, a population comprising 196 recombinant inbred lines (RILs) was constructed from two parents, Luozhen No.1 and Zhengyumai 9987, which differ regarding their total glutenin and its fraction contents (except for the By fraction). Forty-one additive Quantitative Trait Loci (QTL) were detected in four environments over two years. These QTL explained 1.3% - 53.4% of the phenotypic variation in the examined traits. Forty-three pairs of epistatic QTL (E-QTL) were detected in the RIL population across four environments. The QTL controlling the content of total glutenin and its seven fractions were detected in clusters. Seven clusters enriched with QTL for more than three traits were identified, including a QTL cluster 6AS-3, which was revealed as a novel genetic locus for glutenin and related traits. Kompetitive Allele-Specific PCR (KASP) markers developed from the main QTL cluster 1DL-2 and the previously developed KASP marker for the QTL cluster 6AS-3 were validated as significantly associated with the target traits in the RIL population and in natural varieties. CONCLUSIONS: This study identified novel genetic loci related to glutenin and its seven fractions. Additionally, the developed KASP markers may be useful for the marker-assisted selection of varieties with high glutenin fraction content and for identifying individuals in the early developmental stages without the need for phenotyping mature plants. On the basis of the results of this study and the KASP markers described herein, breeders will be able to efficiently select wheat lines with favorable glutenin properties and develop elite lines with high glutenin subunit contents.

Identification of genomic regions affecting grain peroxidase activity in bread wheat using genome-wide association study.

BACKGROUND: Peroxidase (POD) activity plays an important role in flour-based product quality, which is mainly associated with browning and bleaching effects of flour. Here, we performed a genome-wide association study (GWAS) on POD activity using an association population consisted with 207 wheat world-wide collected varieties. Our study also provide basis for the genetic improvement of flour color-based quality in wheat. RESULTS: Twenty quantitative trait loci (QTLs) were detected associated with POD activity, explaining 5.59-12.67% of phenotypic variation. Superior alleles were positively correlated with POD activity. In addition, two SNPs were successfully developed to KASP (Kompetitive Allele-Specific PCR) markers. Two POD genes, TraesCS2B02G615700 and TraesCS2D02G583000, were aligned near the QTLs flanking genomic regions, but only TraesCS2D02G583000 displayed significant divergent expression levels (P < 0.001) between high and low POD activity varieties in the investigated association population. Therefore, it was deduced to be a candidate gene. The expression level of TraesCS2D02G583000 was assigned as a phenotype for expression GWAS (eGWAS) to screen regulatory elements. In total, 505 significant SNPs on 20 chromosomes (excluding 4D) were detected, and 9 of them located within 1 Mb interval of TraesCS2D02G583000. CONCLUSIONS: To identify genetic loci affecting POD activity in wheat grain, we conducted GWAS on POD activity and the candidate gene TraesCS2D02G583000 expression. Finally, 20 QTLs were detected for POD activity, whereas two QTLs associated SNPs were converted to KASP markers that could be used for marker-assisted breeding. Both cis- and trans-acting elements were revealed by eGWAS of TraesCS2D02G583000 expression. The present study provides genetic loci for improving POD activity across wide genetic backgrounds and largely improved the selection efficiency for breeding in wheat.

Pseudomonas nanhaiensis sp. nov., a lipase-producing bacterium isolated from deep-sea sediment of the South China Sea.

A bacterial lipase producing bacterium, designated SCS 2-3, was isolated from deep-sea sediment of the South China Sea. Phylogenetic analysis based on the 16S rRNA sequence revealed that strain SCS2-3 belonged to the genus Pseudomonas and had 98.56% similarity to P. xinjiangensis NRRL B-51270T as the closest relative strain. MLSA using four protein-coding genes (dnaK, gyrA, recA, and rpoB) showed strain SCS 2-3 to form a separate branch. ANI and in silico DDH values between strain SCS 2-3 and related type strains of Pseudomonas were less than 81.51% and 23.80%, respectively. Genome comparison showed that strain SCS 2-3 shared 1875 core gene families with other eight closely related type strains in Pseudomonas, and the number of strain-unique genes was 263. Through gene annotations, genes related to lipase were found in the genome. Furthermore, a combination of phenotypic, chemotaxonomic, phylogenetic and genotypic data clearly indicated that strain SCS 2-3 represents a novel species of the genus Pseudomonas, for which the name Pseudomonas nanhaiensis sp. nov. is proposed. The type strain is SCS 2-3T (= GDMCC 1.2219T = JCM 34440T).

In-depth genetic analysis reveals conditioning of polyphenol oxidase activity in wheat grains by cis regulation of TaPPO2A-1 expression level.

Time-dependent darkening and discoloration of wheat product caused by high polyphenol oxidase enzymes (PPO) activity is the most undesirable character in wheat processing industry. We performed GWAS of PPO activity in wheat grains utilizing an association panel and identified 22 significant SNPs. The most significant GWAS peak on chromosome 2A was verified by QTL analysis of PPO activity. The candidate gene for this GWAS peak was identified as TaPPO2A-1, which was the highest expressed PPO gene in wheat grains. The expression level of TaPPO2A-1 was significantly correlated with PPO activity. The most significant association signal for GWAS of the expression values of TaPPO2A-1 pinpointed to the genomic region containing TaPPO2A-1. The results suggested that cis regulation of TaPPO2A-1 expression is the key factor in regulation of PPO activity in wheat grains. The conclusion was further enhanced by haplotype analysis of seven SNPs in the promoter of TaPPO2A-1.

Modular Assembly of Ordered Hydrophilic Proteins Improve Salinity Tolerance in Escherichia coli.

Most late embryogenesis abundant group 3 (G3LEA) proteins are highly hydrophilic and disordered, which can be transformed into ordered α-helices to play an important role in responding to diverse stresses in numerous organisms. Unlike most G3LEA proteins, DosH derived from Dinococcus radiodurans is a naturally ordered G3LEA protein, and previous studies have found that the N-terminal domain (position 1-103) of DosH protein is the key region for its folding into an ordered secondary structure. Synthetic biology provides the possibility for artificial assembling ordered G3LEA proteins or their analogues. In this report, we used the N-terminal domain of DosH protein as module A (named DS) and the hydrophilic domains (DrHD, BnHD, CeHD, and YlHD) of G3LEA protein from different sources as module B, and artificially assembled four non-natural hydrophilic proteins, named DS + DrHD, DS + BnHD, DS + CeHD, and DS + YlHD, respectively. Circular dichroism showed that the four hydrophile proteins were highly ordered proteins, in which the α-helix contents were DS + DrHD (56.1%), DS + BnHD (53.7%), DS + CeHD (49.1%), and DS + YLHD (64.6%), respectively. Phenotypic analysis showed that the survival rate of recombinant Escherichia coli containing ordered hydrophilic protein was more than 10% after 4 h treatment with 1.5 M NaCl, which was much higher than that of the control group. Meanwhile, in vivo enzyme activity results showed that they had higher activities of superoxide dismutase, catalase, lactate dehydrogenase and less malondialdehyde production. Based on these results, the N-terminal domain of DosH protein can be applied in synthetic biology due to the fact that it can change the order of hydrophilic domains, thus increasing stress resistance.

Skermanella pratensis sp. nov., isolated from meadow soil, and emended description of the genus Skermanella.

A novel Gram-stain-negative, light pink-coloured, short rod-shaped, designated strain W17T, was isolated from a meadow soil sample collected from Xinjiang, PR China. The 16S rRNA gene sequence analysis indicated that strain W17T was related most closely to Skermanella rosea M1T (98.72 %) and Skermanella mucosa 8-14-6T (98.44 %). However, strain W17T showed a low level of DNA-DNA relatedness to S. rosea M1T (32.4±2.6 %) and S. mucosa 8-14-6T (33.5±0.1 %). The genome size of the novel strain was 5.87 Mb and the genomic DNA G+C content was 67.27 mol%. The only respiratory quinone of strain W17T was Q-10. Diphosphatidylglycerol, phosphatidylglycerol. phosphatidylethanolamine and phosphatidylcholine were the major polar lipids. The predominant cellular fatty acids were C18 : 1ω6c and/or C18 : 1ω7c (48.53 %), C16 : 0 (20.88 %) and C18 : 0 (14.92 %). The phylogenetic, phenotypic and chemotaxonomic data showed that strain W17T represents a novel species of the genus Skermanella, for which the name Skermanella pratensis sp. nov. is proposed. The type strain is W17T (=GDMCC 1.1392T=KCTC 62434T).

Ornithinimicrobium pratense sp. nov., isolated from meadow soil.

A novel Gram-stain-positive, yellow, short-rod-shaped or coccoid bacterial strain, W204T, was isolated from a soil sample collected from Jiadengyu national forest park in China and characterized using a polyphasic approach. The cell-wall peptidoglycan contained ornithine as the diagnostic diamino acid. 16S rRNA gene sequence analysis indicated that strain W204T was closely related to Ornithinimicrobium flavum CPCC 203535T (97.4 %, similarity), Serinicoccus profundi CGMCC 4.5582T (96.9 %), Serinicoccus sediminis GP-T3-3T (96.8 %), Serinicoccus hydrothermalis JLT9T (96.7 %), Ornithinimicrobium cerasi CPCC 203383T (96.6 %) and Ornithinimicrobium kibberense K22-20T (96.6 %). However, the digital DNA-DNA genome hybridization value between strain W204T and the closest related strain O. flavum CPCC 203535T was 21.90 %. Complete genome analyses revealed that the size of the genome was 3.54 Mb and the genomic DNA G+C content was 70.79 mol%. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unidentified glycolipid, an unidentified phospholipid and an unidentified lipid. The major menaquinone was MK-8(H4). The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and C16 : 0. The phenotypic, chemotaxonomic and phylogenetic data suggested that strain W204T should be classified as representative of a novel species of the genus Ornithinimicrobium, for which the name Ornithinimicrobium pratense sp. nov. is proposed. The type strain is W204T (=GDMCC 1.1391T=KCTC 49237T).

The Novel ncRNA OsiR Positively Regulates Expression of katE2 and Is Required for Oxidative Stress Tolerance in Deinococcus radiodurans.

Deinococcus radiodurans is a polyextremophilic bacterium well known for its extreme resistance to irradiation, oxidative stress, and other damaging conditions. Many small noncoding RNAs (ncRNAs) in D. radiodurans have been identified by deep sequencing analysis and computational predictions. However, the precise roles of ncRNAs and their target genes in the oxidative stress response have not been investigated. Here, we report the identification and characterization of a novel ncRNA named OsiR (for oxidative stress-induced ncRNA). Oxidative stress tolerance analysis showed that deleting osiR significantly decreased viability, total antioxidant capacity, and catalase activity in D. radiodurans under oxidative stress conditions. Comparative phenotypic and qRT-PCR analyses of an osiR mutant identify a role of OsiR in regulating the expression of the catalase gene katE2. Microscale thermophoresis and genetic complementation showed that a 21-nt sequence in the stem-loop structure of OsiR (204-244 nt) directly base pairs with its counterpart in the coding region of katE2 mRNA (843-866 nt) via a 19 nt region. In addition, deletion of katE2 caused a significant reduction of catalase activity and oxidative stress tolerance similar to that observed in an osiR mutant. Our results show that OsiR positively regulates oxidative stress tolerance in D. radiodurans by increasing the mRNA stability and translation efficiency of katE2. This work provides a new regulatory pathway mediated by ncRNA for the oxidative stress response that most likely contributes to the extreme tolerances of D. radiodurans.

Identification of Novel Genomic Regions and Superior Alleles Associated with Zn Accumulation in Wheat Using a Genome-Wide Association Analysis Method.

Micronutrient deficiencies, and especially zinc (Zn) deficiency, pose serious health problems to people who mainly depend on cereal-based diets. Here, we performed a genome-wide association study (GWAS) to detect the genetic basis of the Zn accumulation in wheat (Triticum aestivum L.) grains with a diversity panel of 207 bread wheat varieties. To uncover authentic quantitative trait loci (QTL) controlling Zn accumulation, the varieties were planted in three locations. In total, 29 unique loci associated with Zn grain accumulation were identified. Notably, seven non-redundant loci located on chromosomes 1B, 3B, 3D, 4A, 5A, 5B, and 7A, were detected at least in two environments. Of these quantitative trait loci (QTL), six coincided with known QTL or genes, whereas the highest effect QTL on chromosome 3D identified in this study was not reported previously. Searches of public databases revealed that the seven identified QTL coincided with seven putative candidate genes linked to Zn accumulation. Among these seven genes, NAC domain-containing protein gene (TraesCS3D02G078500) linked with the most significant single nucleotide polymorphism (SNP) AX-94729264 on chromosome 3D was relevant to metal accumulation in wheat grains. Results of this study provide new insights into the genetic architecture of Zn accumulation in wheat grains.

RNA-Seq-Based Comparative Transcriptome Analysis Highlights New Features of the Heat-Stress Response in the Extremophilic Bacterium Deinococcus radiodurans.

Deinococcus radiodurans is best known for its extraordinary resistance to diverse environmental stress factors, such as ionizing radiation, ultraviolet (UV) irradiation, desiccation, oxidation, and high temperatures. The heat response of this bacterium is considered to be due to a classical, stress-induced regulatory system that is characterized by extensive transcriptional reprogramming. In this study, we investigated the key functional genes involved in heat stress that were expressed and accumulated in cells (R48) following heat treatment at 48 °C for 2 h. Considering that protein degradation is a time-consuming bioprocess, we predicted that to maintain cellular homeostasis, the expression of the key functional proteins would be significantly decreased in cells (RH) that had partly recovered from heat stress relative to their expression in cells (R30) grown under control conditions. Comparative transcriptomics identified 15 genes that were significantly downregulated in RH relative to R30, seven of which had previously been characterized to be heat shock proteins. Among these genes, three hypothetical genes (dr_0127, dr_1083, and dr_1325) are highly likely to be involved in response to heat stress. Survival analysis of mutant strains lacking DR_0127 (a DNA-binding protein), DR_1325 (an endopeptidase-like protein), and DR_1083 (a hypothetical protein) showed a reduction in heat tolerance compared to the wild-type strain. These results suggest that DR_0127, DR_1083, and DR_1325 might play roles in the heat stress response. Overall, the results of this study provide deeper insights into the transcriptional regulation of the heat response in D. radiodurans.

Ectopic Expression of BnaC.CP20.1 Results in Premature Tapetal Programmed Cell Death in Arabidopsis.

Tapetal programmed cell death (PCD) is essential in pollen grain development, and cysteine proteases are ubiquitous enzymes participating in plant PCD. Although the major papain-like cysteine proteases (PLCPs) have been investigated, the exact functions of many PLCPs are still poorly understood in PCD. Here, we identified a PLCP gene, BnaC.CP20.1, which was closely related to XP_013596648.1 from Brassica oleracea. Quantitative real-time PCR analysis revealed that BnaC.CP20.1 expression was down-regulated in male-sterile lines in oilseed rape, suggesting a connection between this gene and male sterility. BnaC.CP20.1 is especially active in the tapetum and microspores in Brassica napus from the uninucleate stage until formation of mature pollen grains during anther development. On expression of BnaC.CP20.1 prior to the tetrad stage, BnA9::BnaC.CP20.1 transgenic lines in Arabidopsis thaliana showed a male-sterile phenotype with shortened siliques containing fewer or no seeds by self-crossing. Scanning electron microscopy indicated that the reticulate exine was defective in aborted microspores. Callose degradation was delayed and microspores were not released from the tetrad in a timely fashion. Additionally, the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay indicated that BnaC.CP20.1 ectopic expression led to premature tapetal PCD. Transmission electron microscopy analyses further demonstrated that the pollen abortion was due to the absence of tectum connections to the bacula in the transgenic anthers. These findings suggest that timely expression of BnaC.CP20.1 is necessary for tapetal degeneration and pollen wall formation.