Reference Gene Selection for qRT-PCR Normalization in Iris germanica L.

Quantitative real-time PCR(qPCR)is an effective and widely used method to analyze expression patterns of target genes.Selection of stable reference genes is a prerequisite for accurate normalization of target gene expression by qRT-PCR.In Iris germanica L.,no studies have yet been published regarding the evaluation of potential reference genes.In this study,nine candidate reference genes were assessed at different flower developmental stages and in different tissues by four different algorithms(GeNorm,NormFinder,BestKeeper,and RefFinder).The results revealed that ACT11(Actin 11)and EF1α(Elongation factor 1 alpha)were the most stable reference genes in different tissues,whereas TUA(Tubulin alpha)and UBC9(Ubiquitin-protein ligase 9)were the most stable ones in different flower developmental stages.UBC9 and ACT11 were the most stable reference genes in all of the tested samples,while the SAMDC(S-Adenosylmethionine decarboxylase)showed the least stability.Finally,to validate the suitability of the selected reference genes,the relative expression level of IgTPS(beta-caryophyllene synthase)was assessed and highlighted the importance of suitable reference gene selection.This work constitutes the first systematic evaluation of potential reference genes in I.germanica and provides guidelines for future research on gene function and molecular mechanisms on I.germanica and related species.

The chromosome-level Stevia genome provides insights into steviol glycoside biosynthesis

Stevia(Stevia rebaudiana Bertoni)is well known for its very sweet steviol glycosides(SGs)consisting of a common tetracyclic diterpenoid steviol backbone and a variable glycone.Steviol glycosides are 150–300 times sweeter than sucrose and are used as natural zero-calorie sweeteners.However,the most promising compounds are biosynthesized in small amounts.Based on Illumina,PacBio,and Hi-C sequencing,we constructed a chromosome-level assembly of Stevia covering 1416 Mb with a contig N50 value of 616.85 kb and a scaffold N50 value of 106.55 Mb.More than four-fifths of the Stevia genome consisted of repetitive elements.We annotated 44,143 high-confidence protein-coding genes in the high-quality genome.Genome evolution analysis suggested that Stevia and sunflower diverged~29.4 million years ago(Mya),shortly after the whole-genome duplication(WGD)event(WGD-2,~32.1 Mya)that occurred in their common ancestor.Comparative genomic analysis revealed that the expanded genes in Stevia were mainly enriched for biosynthesis of specialized metabolites,especially biosynthesis of terpenoid backbones,and for further oxidation and glycosylation of these compounds.We further identified all candidate genes involved in SG biosynthesis.Collectively,our current findings on the Stevia reference genome will be very helpful for dissecting the evolutionary history of Stevia and for discovering novel genes contributing to SG biosynthesis and other important agronomic traits in future breeding programs.

Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experimentswere performed to explore the impact of sulfur nanoparticles(SNPs)on growth,Cu accumulation,and physiological and biochemical responses of oilseed rape(Brassica napus L.)inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure.Cu exerted severe phytotoxicity and inhibited plant growth.SNPs application enhanced the shoot height,root length,and dry weight of shoot and root by 34.6%,282%,41.7%and 37.1%,respectively,over Cu treatment alone,while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde(MDA)levels in shoots and roots were decreased by 37.6%,35%,28.4%and 26.8%.Further,the increases in superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX),glutathione reductase(GR)and glutathione S-transferase(GST)enzyme activities caused by Cu stress were mitigated in shoots(10.9%–37.1%)and roots(14.6%–35.3%)with SNPs addition.SNPs also positively counteracted the negative effects on shoot K,Ca,P,Mg,Mn,Zn and Fe contents and root K,Ca,Mg and Mn contents from Cu exposure alone,and significantly promoted the nutrients accumulation in plant.Additionally,in comparison with common bulk sulfur particles(BSPs)and sulfate,SNPs showed more positive effects on promoting growth in shoots(6.7%and 19.5%)and roots(10.9%and 15.1%),as well as lowering the shoot Cu content(40.1%and 43.3%)under Cu stress.Thus,SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.

MEAN SQUARE STABILITY AND DISSIPATIVITY OF SPLIT- STEP THETA METHOD FOR NONLINEAR NEUTRAL STOCHASTIC DELAY DIFFERENTIAL EQUATIONS WITH POISSON JUMPS

In this paper, a split-step 0 （SST） method is introduced and used to solve the non- linear neutral stochastic differential delay equations with Poisson jumps （NSDDEwPJ）. The mean square asymptotic stability of the SST method for nonlinear neutral stochastic differential equations with Poisson jumps is studied. It is proved that under the one-sided Lipschitz condition and the linear growth condition, the SST method with ∈ E （0, 2 -√2） is asymptotically mean square stable for all positive step sizes, and the SST method with ∈ E （2 -√2, 1） is asymptotically mean square stable for some step sizes. It is also proved in this paper that the SST method possesses a bounded absorbing set which is independent of initial data, and the mean square dissipativity of this method is also proved.

Correlation between acne and Northwest dryness syndrome in Xinjiang autonomous region of China

OBJECTIVE： To analyze the correlation between ac- he and Northwest dryness syndrome in the Xinji- ang region to provide an epidemiological founda- tion for the prevention and treatment of acne in the region. METHODS： The correlations among acne, clinical syndromes of Northwest dryness syndrome, and Northwest dryness syndrome were evaluated using the syndrome fitness index and canonical correla- tion analysis. RESULTS： The ache group had a Northwest drynesssyndrome rate of 24.13%, and the control group 10.34% （χ2=7.733, P〈0.01）. There was no significant difference in the fitness index for acne and for the sub-syndromes of Northwest dryness syndrome （P〉 0.05）. The first canonical correlation coefficient was 0.5656 （P〈0.01）. The acne-dependent variable group had the largest damp-heat syndrome load （0.8709）, and the independent variable had the largest lung-heart-spleen pyretic dryness load （0.6766）. CONCLUSION： Northwest dryness syndrome is a risk factor for ache in the Xinjiang region. Exoge- nous dryness and endogenous damp are frequent- ly seen as subsyndromes in Northwest dryness syn- drome in acne patients in the region. Acne was cor- related with the damp-heat and lung-heart-spleen pyretic dryness sub-syndromes of Northwest dry- ness syndrome.

Identification of potential electrotrophic microbial community in paddy soils by enrichment of microbial electrolysis cell biocathodes

Electrotrophs are microbes that can receive electrons directly from cathode in a microbial electrolysis cell(MEC).They not only participate in organic biosynthesis,but also be crucial in cathode-based bioremediation.However,little is known about the electrotrophic community in paddy soils.Here,the putative electrotrophs were enriched by cathodes of MECs constructed from five paddy soils with various properties using bicarbonate as an electron acceptor,and identified by 16S rRNA-gene based Illumina sequencing.The electrons were gradually consumed on the cathodes,and 25%–45% of which were recovered to reduce bicarbonate to acetic acid during MEC operation.Firmicutes was the dominant bacterial phylum on the cathodes,and Bacillus genus within this phylum was greatly enriched and was the most abundant population among the detected putative electrotrophs for almost all soils.Furthermore,several other members of Firmicutes and Proteobacteria may also participate in electrotrophic process in different soils.Soil pH,amorphous iron and electrical conductivity significantly influenced the putative electrotrophic bacterial community,which explained about 33.5% of the community structural variation.This study provides a basis for understanding the microbial diversity of putative electrotrophs in paddy soils,and highlights the importance of soil properties in shaping the community of putative electrotrophs.

CONVERGENCE AND MEAN-SQUARE STABILITY OF EXPONENTIAL EULER METHOD FOR SEMI-LINEAR STOCHASTIC DELAY INTEGRO-DIFFERENTIAL EQUATIONS

In this paper,the numerical methods for semi-linear stochastic delay integro-difFerential equations are studied.The uniqueness,existence and stability of analytic solutions of semi-linear stochastic delay integro-differential equations are studied and some suitable conditions for the mean-square stability of the analytic solutions are also obtained.Then the numerical approximation of exponential Euler method for semi-linear stochastic delay integro-differential equations is constructed and the convergence and the stability of the numerical method are studied.It is proved that the exponential Euler method is convergent with strong order 1/2 and can keep the mean-square exponential stability of the analytical solutions under some restrictions on the step size.In addition,numerical experiments are presented to confirm the theoretical results.