Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

Genome-wide scan for selection signatures based on whole-genome re-sequencing in Landrace and Yorkshire pigs

We performed a genome-wide scan to detect selection signatures that showed evidence of positive selection in the domestication process by re-sequencing the whole genomes of Landrace and Yorkshire pigs.Fifteen annotated elements with 13 associated genes were identified using the Z-transformed FST(Z(FST))method,and 208 annotated elements with 140 associated genes were identified using the Z-transformed heterozygosity(ZHp)method.The functional analysis and the results of previous studies showed that most of the candidate genes were associated with basic metabolism,disease resistance,cellular processes,and biochemical signals,and several were related to body morphology and organs.They included PPP3CA,which plays an essential role in the transduction of intracellular Ca2+-mediated signals,and WWTR1,which plays a pivotal role in organ size control and tumor suppression.These results suggest that genes associated with body morphology were subject to selection pressure during domestication,whereas genes involved in basic metabolism and disease resistance were subject to selection during artificial breeding.Our findings provide new insights into the potential genetic variation of phenotypic diversity in different pig breeds and will help to better understand the selection effects of modern breeding in Landrace and Yorkshire pigs.

Cost-effective low-coverage whole-genome sequencing assay for the risk stratification of gastric cancer

BACKGROUND Gastric cancer(GC), a multifactorial disease, is caused by pathogens, such as Helicobacter pylori(H. pylori) and Epstein-Barr virus(EBV), and genetic components.AIM To investigate microbiomes and host genome instability by cost-effective,low-coverage wholegenome sequencing,as biomarkers for GC subtyping.METHODS Samples from 40 GC patients were collected from Taizhou Hospital,Zhejiang Province,affiliated with Wenzhou Medical University.DNA from the samples was subjected to low-coverage wholegenome sequencing with a median genome coverage of 1.86×(range:1.03×to 3.17×) by Illumina×10,followed by copy number analyses using a customized bioinformatics workflow ultrasensitive chromosomal aneuploidy detector.RESULTS Of the 40 GC samples,20 (50%) were found to be enriched with microbiomes.EBV DNA was detected in 5 GC patients (12.5%).H.pylori DNA was found in 15 (37.5%) patients.The other 20(50%) patients were found to have relatively higher genomic instability.Copy number amplifications of the oncogenes,ERBB2 and KRAS,were found in 9 (22.5%) and 7 (17.5%) of the GC samples,respectively.EBV enrichment was found to be associated with tumors in the gastric cardia and fundus.H.pylori enrichment was found to be associated with tumors in the pylorus and antrum.Tumors with elevated genomic instability showed no localization and could be observed in any location.Additionally,H.pylori-enriched GC was found to be associated with the Borrmann type Ⅱ/Ⅲ and gastritis history.EBV-enriched GC was not associated with gastritis.No statistically significant correlation was observed between genomic instability and gastritis.Furthermore,these three different molecular subtypes showed distinct survival outcomes (P=0.019).EBV-positive tumors had the best prognosis,whereas patients with high genomic instability (CIN+) showed the worst survival.Patients with H.pylori infection showed intermediate prognosis compared with the other two subtypes.CONCLUSION Thus,using low-coverage whole-genome sequencing,GC can be classified into three categories based on disease etiology;this classification may prove useful for GC diagnosis and precision medicine.

Population genetics of marmosets in Asian primate research centers and loci associated with epileptic risk revealed by whole-genome sequencing

The common marmoset(Callithrix jacchus)has emerged as a valuable nonhuman primate model in biomedical research with the recent release of high-quality reference genome assemblies.Epileptic marmosets have been independently reported in two Asian primate research centers.Nevertheless,the population genetics within these primate centers and the specific genetic variants associated with epilepsy in marmosets have not yet been elucidated.Here,we characterized the genetic relationships and risk variants for epilepsy in 41 samples from two epileptic marmoset pedigrees using whole-genome sequencing.We identified 14558184 single nucleotide polymorphisms(SNPs)from the 41 samples and found higher chimerism levels in blood samples than in fingernail samples.Genetic analysis showed fourth-degree of relatedness among marmosets at the primate centers.In addition,SNP and copy number variation(CNV)analyses suggested that the WW domain-containing oxidoreductase(WWOX)and Tyrosine-protein phosphatase nonreceptor type 21(PTPN21)genes may be associated with epilepsy in marmosets.Notably,KCTD18-like gene deletion was more common in epileptic marmosets than control marmosets.This study provides valuable population genomic resources for marmosets in two Asian primate centers.Genetic analyses identified a reasonable breeding strategy for genetic diversity maintenance in the two centers,while the case-control study revealed potential risk genes/variants associated with epilepsy in marmosets.

The bisulfite genomic sequencing protocol

The bisulfite genomic sequencing (BGS) protocol has gained worldwide popularity as the method of choice for analyzing DNA methylation. It is this popular because it is a powerful protocol and it may be coupled with many other applications. However, users often run into a slew ofproblems, including incomplete conversion,overly degraded DNA, sub-optimal PCR amplifications, false positives, uninformative results, or altogether failed experiments. We pinpoint the reasons why these problems arise and carefully explain the critical steps toward accomplishing a successful experiment step-by-step. This protocol has worked successfully (>99.9% conversion) on as little as 100 ng of DNA derived from nearly 10-year-old DNA samples extracted from whole blood stored at -80°C and resulted in enough converted DNA for more than 50 PCRreactions. The aim of this article is to makelearning and usage of BGS easier, more efficient and standardized for all users.

Safety assessment of a novel marine multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 according to phenotype and whole genome-sequencing analysis

The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from marine mangrove microorganisms.Its safety and probiotic properties were assessed in accordance with phenotype and whole-genome sequencing analysis.Results showed that the genes and phenotypic expression of related virulence,antibiotic resistance and retroelement were rarely found.Hyphal morphogenesis genes(SIT4,HOG1,SPA2,ERK1,ICL1,CST20,HSP104,TPS1,and RHO1)and phospholipase secretion gene(VPS4)were annotated.True hyphae and phospholipase were absent.Only one retroelement(Tad1-65_BG)was found.Major biogenic amines(BAs)encoding genes were absent,except for spermidine synthase(JA9_002594),spermine synthase(JA9_004690),and tyrosine decarboxylase(inx).The production of single BAs and total BAs was far below the food-defined thresholds.GXDK6 had no resistance to common antifungal drugs.Virulence enzymes,such as gelatinase,DNase,hemolytic,lecithinase,and thrombin were absent.Acute toxicity test with mice demonstrated that GXDK6 is safe.GXDK6 has a good reproduction ability in the simulation gastrointestinal tract.GXDK6 also has a strong antioxidant ability,β-glucosidase,and inulinase activity.To sum up,GXDK6 is considered as a safe probiotic for human consumption and food fermentation.

A stage-scanning laser confocal microscope and protocol for DNA methylation sequencing

Recent understanding of the role of epigenetic regulation in health and disease has necessitated the development of newer and efficient methods to map the methylation pattern of target gene. In this article we report construction of a stage-scanning laser confocal microscope (SLCM) and associated protocol that determines the methylation status of target gene. We have adapted restricted Sanger’s sequencing where fluorescine labeled primers and dideoxy guanine fraction alone are used for target amplification and termination at cytosine positions. Amplified ssDNA bands are separated in 6% denaturing PAGE and scanned using SLCM to sequence the positions of methylated cytosines. We demonstrate that our me- thodology can detect < 100 femtomoles of DNA, and resolve the position of cytosine within ± 2 nucleotide. In a calibration run using a designer DNA of 99 bases, our methodology had resolved all the 11 cytosine positions of the DNA. We have further demonstrated the utility of apparatus by mapping methylation status in the Exon-1 region of a gene, E-Cadherin, in the plasma DNA sample of a healthy subject. We believe our approach constitute a low cost alternative to conventional DNA sequencers and can help develop methylation based DNA biomarkers for the diagnosis of disease and in therapeutics.

Whole-genome Sequencing Reveals Autooctoploidy in Chinese Sturgeon and Its Evolutionary Trajectories

The order Acipenseriformes,which includes sturgeons and paddlefishes,represents“living fossils”with complex genomes that are good models for understanding whole-genome duplication(WGD)and ploidy evolution in fishes.Here,we sequenced and assembled the first high-quality chromosome-level genome for the complex octoploid Acipenser sinensis(Chinese sturgeon),a critically endangered species that also represents a poorly understood ploidy group in Acipenseriformes.Our results show that A.sinensis is a complex autooctoploid species containing four kinds of octovalents(8n),a hexavalent(6n),two tetravalents(4n),and a divalent(2n).An analysis taking into account delayed rediploidization reveals that the octoploid genome composition of Chinese sturgeon results from two rounds of homologous WGDs,and further provides insights into the timing of its ploidy evolution.This study provides the first octoploid genome resource of Acipenseriformes for understanding ploidy compositions and evolutionary trajectories of polyploid fishes.

Complete Genome Sequencing and Analysis of Rehmannia Mosaic Virus Isolate from Shanxi Province

Using double-stranded RNA(dsRNA)technology and sequence-independent amplification(SIA),the molecular identification on infected Rehmannia glutinosa in the field with mosaic symptoms was performed and the whole-genome of the Rehmannia mosaic virus(ReMV)Shanxi isolate(ReMV-SX)was sequenced.Sequencing analysis showed that the virus that infected Rehmannia glutinosa was Rehmannia mosaic virus(ReMV).The full-length of the obtained ReMV-SX sequence(GenBank accession no.JX575184)was 6395 nt,containing four open reading frames(ORFs).The sequence homology analysis of the complete nucleotide sequence showed that ReMV-SX was 93.8%-97.0%homologous to ReMV in Tobamovirus subgroup Ⅰ,while only 49.8%-58.9%homologous to the isolates in subgroups Ⅱ and Ⅲ of the same genus.Phylogenetic analysis showed that ReMV-SX and ReMV-Henan formed a separate branch and had the closest genetic relationship.The results laid the foundation for ongoing researches in the taxonomic status and evolution of ReMV and for further investigating the pathogenic mechanism of ReMV infecting Rehmannia glutinosa.

Molecular diagnosis of autosomal recessive cerebellar ataxia in the whole exome/genome sequencing era

Autosomal recessive cerebellar ataxias(ARCA) are a clinically and genetically heterogeneous group of rare neurodegenerative disorders characterized by autosomal recessive inheritance and an early age of onset. Progressive ataxia is usually the prominent symptom and is often associated with other neurological or additional features. ARCA classification still remains controversial even though different approaches have been proposed over the years. Furthermore, ARCA molecular diagnosis has been a challenge due to phenotypic overlap and increased genetic heterogeneity observed within this group of disorders. Friedreich's ataxia and ataxia telangiectasia have been reported as the most frequent and well-studied forms of ARCA. Significant progress in understanding the genetic etiologies of the ARCA has been achieved during the last 15 years. The methodological revolution that has been observed in genetics over the last few years has contributed significantly to the molecular diagnosis of rare diseases including the ARCAs. Development of high throughput technologies has resulted in the identification of new ARCA genes and novel mutations in known ARCA genes. Therefore,an improvement in the molecular diagnosis of ARCA is expected. Moreover, based on the fact that many patients still remain undiagnosed, additional forms of ataxia are expected to be identified. We hereby review the current knowledge on the ARCAs, focused on the genetic findings of the most common forms that were molecularly characterized before the whole exome/genome era, as well as the most recently described forms that have been elucidated with the use of these novel technologies. The significant contribution of wholeexome sequencing or whole-genome sequencing in the molecular diagnosis of ARCAs is discussed.

Whole-genome sequencing identifies functional genes for environmental adaptation in Chinese sheep

Sheep(Ovis aries),among the first domesticated species,are now globally widespread and exhibit remarkable adaptability to diverse environments.In this study,we perform whole-genome sequencing of266 animals from 18 distinct Chinese sheep populations,each displaying unique phenotypes indicative of adaptation to varying environmental conditions.Integrating 131 environmental factors with single nucleotide polymorphism variations,we conduct a comprehensive genetic-environmental association analysis.This analysis identifies 35 key genes likely integral to the environmental adaptation of sheep.The functions of these genes include fat tail formation(HOXA10,HOXA11,JAZF1),wool characteristics(FER,FGF5,MITF,PDE4B),horn phenotypes(RXFP2),reproduction(HIBADH,TRIM71,C6H4orf22),and growth traits(ADGRL3,TRHDE).Notably,we observe a significant correlation between the frequency of missense mutations in the PAPSS2 and RXFP2 genes and variations in altitude.Our study reveals candidate genes for adaptive variation in sheep and demonstrates the diversity in how sheep adapt to their environment.

Whole-genome sequencing identifies novel genes for autism in Chinese trios

Autism spectrum disorder(ASD)is a neurodevelopmental disorder with high genetic heritability but heterogeneity.Fully understanding its genetics requires whole-genome sequencing(WGS),but the ASD studies utilizing WGS data in Chinese population are limited.In this study,we present a WGS study for 334 individuals,including 112 ASD patients and their non-ASD parents.We identified 146 de novo variants in coding regions in 85 cases and 60 inherited variants in coding regions.By integrating these variants with an association model,we identified 33 potential risk genes(P<0.001)enriched in neuron and regulation related biological process.Besides the well-known ASD genes(SCN2A,NF1,SHANK3,CHD8 etc.),several high confidence genes were highlighted by a series of functional analyses,including CTNND1,DGKZ,LRP1,DDN,ZNF483,NR4A2,SMAD6,INTS1,and MRPL12,with more supported evidence from GO enrichment,expression and network analysis.We also integrated RNA-seq data to analyze the effect of the variants on the gene expression and found 12 genes in the individuals with the related variants had relatively biased expression.We further presented the clinical phenotypes of the proband carrying the risk genes in both our samples and Caucasian samples to show the effect of the risk genes on phenotype.Regarding variants in noncoding regions,a total of 74 de novo variants and 30 inherited variants were predicted as pathogenic with high confidence,which were mapped to specific genes or regulatory features.The number of de novo variants found in patient was significantly associated with the parents’ages at the birth of the child,and gender with trend.We also identified small de novo structural variants in ASD trios.The results in this study provided important evidence for understanding the genetic mechanism of ASD.

Whole-genome sequencing to detect mutations associated with resistance to insecticides and Bt proteins in Spodoptera frugiperda

The fall armyworm(FAW),Spodoptera frugiperda,is a major pest native to the Americas that has recently invaded the Old World.Point mutations in the target-site proteins acetylcholinesterase-1(ace-1),voltage-gated sodium channel(VGSC)and ryanodine receptor(RyR)have been identified in S.frugiperda as major resistance mechanisms to organophosphate,pyrethroid and diamide insecticides respectively.Mutations in the adenosine triphosphate-binding cassette transporter C2 gene(ABCC2)have also been identified to confer resistance to Cry IF protein.In this study,we applied a whole-genome sequencing(WGS)approach to identify point mutations in the target-site genes in 150 FAW individuals collected from China,Malawi,Uganda and Brazil.This approach revealed three amino acid substitutions(A201S,G227A and F290V)of S.frugiperda ace-1,which are known to be associated with organophosphate resistance.The Brazilian population had all three ace-1 point mutations and the 227A allele(mean frequency=0.54)was the most common.Populations from China,Malawi and Uganda harbored two of the three ace-1 point mutations(A201S and F290V)with the 290V allele(0.47-0.58)as the dominant allele.Point mutations in VGSC(T929I,L932F and L1014F)and RyR(I4790M and G4946E)were not detected in any of the 150 individuals.A novel 12-bp insertion mutation in exon 15 of the ABCC2 gene was identified in some of the Brazilian individuals but absent in the invasive populations.Our results not only demonstrate robustness of the WGS-based genomic approach for detection of resistance mutations,but also provide insights for improvement of resistance management tactics in S.frugiperda.

Whole-genome sequencing of monozygotic twins discordant for schizophrenia indicates multiple genetic risk factors for schizophrenia

Schizophrenia is a common disorder with a high heritability, but its genetic architecture is still elusive.We implemented whole-genome sequencing(WGS) analysis of 8 families with monozygotic(MZ) twin pairs discordant for schizophrenia to assess potential association of de novo mutations(DNMs) or inherited variants with susceptibility to schizophrenia. Eight non-synonymous DNMs(including one splicing site) were identified and shared by twins, which were either located in previously reported schizophrenia risk genes(p.V24689 I mutation in TTN, p.S2506 T mutation in GCN1L1, IVS3+1G > T in DOCK1) or had a benign to damaging effect according to in silico prediction analysis. By searching the inherited rare damaging or loss-of-function(LOF) variants and common susceptible alleles from three classes of schizophrenia candidate genes, we were able to distill genetic alterations in several schizophrenia risk genes, including GAD1, PLXNA2, RELN and FEZ1. Four inherited copy number variations(CNVs; including a large deletion at 16p13.11) implicated for schizophrenia were identified in four families, respectively. Most of families carried both missense DNMs and inherited risk variants, which might suggest that DNMs, inherited rare damaging variants and common risk alleles together conferred to schizophrenia susceptibility. Our results support that schizophrenia is caused by a combination of multiple genetic factors, with each DNM/variant showing a relatively small effect size.

Genomic landscapes of Chinese sporadic autism spectrum disordersrevealed by whole-genome sequencing

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with considerable clinical and genetic heterogeneity.In this study,we identified all classes of genomic variants from whole-genome sequencing (WGS) dataset of 32 Chinese trios with ASD,including de novo mutations,inherited variants,copy number variants (CNVs) and genomic structural variants.A higher mutation rate (Poisson test,P<2.2×10^(-16)) in exonic (1.37×10^(-8)) and 3'-UTR regions (1.42×10^(-8)) was revealed in comparison with that of whole genome (1.05×10^(-8)).Using an integrated model,we identified 87 potentially risk genes (P<0.01) from 4832 genes harboring various rare deleterious variants,including CHD8 and NRXN2,implying that the disorders may be in favor to multiple-hit.In particular,frequent rare inherited mutations of several microcephaly-associated genes (ASPM,WDR62,and ZNF335)were found in ASD.In chromosomal structure analyses,we found four de novo CNVs and one de novo chromosomal rearrangement event,including a de novo duplication of UBE3A-containing region at 15q11.2-q13.1,which causes Angelman syndrome and microcephaly,and a disrupted TNR due to de novo chromosomal translocation t (1;5) (q25.1;q33.2).Taken together,our results suggest that abnormalities of centrosomal function and chromatin remodeling of the microcephaly-associated genes may be implicated in pathogenesis of ASD.Adoption of WGS as a new yet efficient technique to illustrate the full genetic spectrum in complex disorders,such as ASD,could provide novel insights into pathogenesis,diagnosis and treatment.

Draft genome sequence of a less-known wild Vigna: Beach pea(V. marina cv. ANBp-14-03)

Beach pea or beach cowpea(Vigna marina(Burm.)Merr.)belongs to the family Fabaceae.It is a close relative of cultivated Vigna species such as adzuki bean(V.angularis),cowpea(V.unguiculata),mung bean(V.radiata),and blackgram(V.mungo),and is distributed throughout the tropics.With its ability to tolerate salt stress,beach pea has great potential to contribute salt-tolerance genes for developing salt-tolerant cultivars in cultivated Vigna species.However,it is still underutilized in Vigna breeding programs.A draft genome sequence of beach pea was generated using a high-throughput next-generation sequencing platform,yielding 23.7 Gb of sequence from 79,929,868 filtered reads.A de novo genome assembly containing 68,731 scaffolds gave an N50 length of 10,272 bp and the assembled sequences totaled 365.6 Mb.A total of 35,448 SSRs,including 3574 compound SSRs,were identified and primer pairs for most of these SSRs were designed.Genome analysis identified 50,670 genes with mean coding sequence length 1042 bp.Phylogenetic analysis revealed highest sequence similarity with V.angularis,followed by V.radiata.Comparison with the V.angularis genome revealed 16,699 SNPs and 2253 InDels and comparison with the V.radiata genome revealed 17,538 SNPs and 2300 InDels.To our knowledge this is the first draft genome sequence of beach pea derived from an accession(ANBp-14-03)adapted locally in the Andaman and Nicobar Islands of India.The draft genome sequence may facilitate the genetic enhancement in cultivated Vigna species.

Differential methylation analysis for bisulfite sequencing using DSS

Bisulfite sequencing(BS-seq)technology measures DNA methylation at single nucleotide resolution.A key task in BSseq data analysis is to identify differentially methylation(DM)under different conditions.Here we provide a tutorial for BS-seq DM analysis using Bioconductor package DSS.DSS uses a beta-binomial model to characterize the sequence counts from BS-seq,and implements rigorous statistical method for hypothesis testing.It provides flexible functionalities for a variety of DM analyses.

Analysis of the genomic landscape of primary central nervous system lymphoma using whole-genome sequencing in Chinese patients

Primary central nervous system lymphoma(PCNSL)is an uncommon non-Hodgkin’s lymphoma with poor prognosis.This study aimed to depict the genetic landscape of Chinese PCNSLs.Whole-genome sequencing was performed on 68 newly diagnosed Chinese PCNSL samples,whose genomic characteristics and clinicopathologic features were also analyzed.Structural variations were identified in all patients with a mean of 349,which did not significantly influence prognosis.Copy loss occurred in all samples,while gains were detected in 77.9%of the samples.The high level of copy number variations was significantly associated with poor progression-free survival(PFS)and overall survival(OS).A total of 263 genes mutated in coding regions were identified,including 6 newly discovered genes(ROBO2,KMT2C,CXCR4,MYOM2,BCLAF1,and NRXN3)detected in≥10%of the cases.CD79B mutation was significantly associated with lower PFS,TMSB4X mutation and high expression of TMSB4X protein was associated with lower OS.A prognostic risk scoring system was also established for PCNSL,which included Karnofsky performance status and six mutated genes(BRD4,EBF1,BTG1,CCND3,STAG2,and TMSB4X).Collectively,this study comprehensively reveals the genomic landscape of newly diagnosed Chinese PCNSLs,thereby enriching the present understanding of the genetic mechanisms of PCNSL.

Integrating Culture-based Antibiotic Resistance Profiles with Whole-genome Sequencing Data for 11,087 Clinical Isolates

Emerging antibiotic resistance is a major global health threat. The analysis of nucleic acid sequences linked to susceptibility phenotypes facilitates the study of genetic antibiotic resistance determinants to inform molecular diagnostics and drug development. We collected genetic data (11,087 newly-sequenced whole genomes) and culture-based resistance profiles (10,991 out of the 11,087 isolates comprehensively tested against 22 antibiotics in total) of clinical isolates including 18 main species spanning a time period of 30 years. Species and drug specific resistance patterns were observed including increased resistance rates for Acinetobacter baumannii to carbapenems and for Escherichia coli to fluoroquinolones. Species-level pan-genomes were constructed to reflect the genetic repertoire of the respective species,including conserved essential genes and known resis-tance factors. Integrating phenotypes and genotypes through species-level pan-genomes allowed to infer gene–drug resistance associations using statistical testing. The isolate collection and the analysis results have been integrated into GEAR-base,a resource available for academic research use free of charge at https://gear-base.com.

Des=gn of efficient simplified genomic DNA and bisulfite sequencing in large plant populations

The next generation sequencing enables generation of high resolution and high throughput data for structure sequence of any genome at a fast declining cost. This opens opportunity for population based genetic and genomic analyses. In many applications, whole genome sequencing or re-sequencing is unnecessary or prohibited by budget limits. The Reduced Representation Genome Sequencing （RRGS）, which sequences only a small proportion of the genome of interest, has been proposed to deal with the situations. Several forms of RRGS are proposed and implemented in the literature. When applied to plant or crop species, the current RRGS protocols shared a key drawback that a significantly high proportion （up to 60%） of sequence reads to be generated may be of non-genomic origin but attributed to chloroplast DNA or rRNA genes, leaving an exceptional low efficiency of the sequencing experiment. We recommended and discussed here the design of optimized simplified genomic DNA and bisulfite sequencing strategies, which may greatly improves efficiency of the sequencing experiments by bringing down the presentation of the undesirable sequencing reads to less than 10% in the whole sequence reads. The optimized RAD- seq and RRBS-seq methods are potentially useful for sequence variant screening and genotyping in large plant/crop populations.