Effect of Ar^+ Implantation and Maize Genome DNA on Autotetraploid Rice

The effect of Ar^＋ beam implantation and maize genome DNA on autotetraploid rice is studied. Better mutation types and higher mutation rates were discovered in M2 of T3 with ion implantation and immersion in maize genome DNA. In the five agronomic categories investigated, the mutation rate of the seed setting rate was 9.1%, and the total mutation rate was 14.8% in the T3. However, the total mutation rate was 2.1% with the treatment of only ion implantation and 1.3% with the treatment of only immersion in maize genome DNA. Mutant FA36（4） was discovered in M1 with ion beam implantation and immersion in maize genome DNA. Its RuBPCase activity, PEPCase activity and seed setting rate were 32%, 153%, and 36.79%, respectively, higher than its parent IR36（4）. Rapid analysis of polymorphicDNA （RAPD） analysis of three M2 plants of FA36（4） （FMI, FM2, FM3） and two controls （purple maize and IR36（4）） were also conducted with 40 random primers. S5-3 was RAPD fragment amplified with a template of purple maize, FM2 and FM3 genome DNA using primer S5. There was no S5-3 in the RAPD pattern of IR36（4） or FMI.

Methylome and transcriptome data integration reveals potential roles of DNA methylation and candidate biomarkers of cow Streptococcus uberis subclinical mastitis

Background:Mastitis caused by different pathogens including Streptococcus uberis(S.uberis)is responsible for huge economic losses to the dairy industry.In order to investigate the potential genetic and epigenetic regulatory mecha‑nisms of subclinical mastitis due to S.uberis,the DNA methylome(whole genome DNA methylation sequencing)and transcriptome(RNA sequencing)of milk somatic cells from cows with naturally occurring S.uberis subclinical mastitis and healthy control cows(n=3/group)were studied.Results:Globally,the DNA methylation levels of CpG sites were low in the promoters and first exons but high in inner exons and introns.The DNA methylation levels at the promoter,first exon and first intron regions were nega‑tively correlated with the expression level of genes at a whole‑genome‑wide scale.In general,DNA methylation level was lower in S.uberis‑positive group(SUG)than in the control group(CTG).A total of 174,342 differentially methylated cytosines(DMCs)(FDR<0.05)were identified between SUG and CTG,including 132,237,7412 and 34,693 DMCs in the context of CpG,CHG and CHH(H=A or T or C),respectively.Besides,101,612 methylation haplotype blocks(MHBs)were identified,including 451 MHBs that were significantly different(dMHB)between the two groups.A total of 2130 differentially expressed(DE)genes(1378 with up‑regulated and 752 with down‑regulated expression)were found in SUG.Integration of methylome and transcriptome data with MethGET program revealed 1623 genes with signifi‑cant changes in their methylation levels and/or gene expression changes(MetGDE genes,MethGET P‑value<0.001).Functional enrichment of genes harboring≥15 DMCs,DE genes and MetGDE genes suggest significant involvement of DNA methylation changes in the regulation of the host immune response to S.uberis infection,especially cytokine activities.Furthermore,discriminant correlation analysis with DIABLO method identified 26 candidate biomarkers,including 6 DE genes,15 CpG‑DMCs and 5 dMHBs that discriminated between SUG and CTG.Conclusion:The integration of methylome and transcriptome of milk somatic cells suggests the possible involve‑ment of DNA methylation changes in the regulation of the host immune response to subclinical mastitis due to S.uberis.The presented genetic and epigenetic biomarkers could contribute to the design of management strategies of subclinical mastitis and breeding for mastitis resistance.

Higher frequency of Yq microdeletions in sperm DNA as compared to DNA isolated from blood

Aim： To determine if Yq microdeletion frequency and loci of deletion are similar in two tissues （blood and sperm） of different embryological origin. Methods： The present study included 52 infertile oligozoospermic cases. In each case, DNA was isolated from blood and sperms and polymerase chain reaction （PCR） microdeletion analysis was done from genomic DNA isolated from both the tissues. The PCR products were analyzed on a 1.8% agarose gel. PCR amplifications found to be negative were repeated at least three times to confirm the deletion of a given marker. Results： Only 1 case harbored microdeletion in blood DNA, whereas 4 cases harbored microdeletion in sperm DNA. Conclusion： The frequency of Yq microdeletions is higher in germ cells as compared to blood. As the majority of infertile couples opt for assisted reproduction procreation techniques （ART）, Yq microdeletion screening from germ cells is important to understand the genetic basis of infertility, to provide comprehensive counseling and most adapted therapeutics to the infertile couple.

A NOVEL HUMAN DNA SEQUENCE WITH TUMOR METASTASIS SUPPRESSIVE ACTIVITY

Objective: To isolate human tumor metastasis suppressive DNA sequence and to study the molecular mechanisms regulating tumor metastasis. Methods: A mouse lung adenocarcinoma cell clone 12 derived from its parent cell line LM2, which had been transduced with normal human genomic DNA, was previously reported. Compared with LM2, the metastatic potential of clone 12 was very much decreased. Clone 12 was used in this study to amplify the human DNA fragments by Inter Alu PCR technique. The human DNA fragments obtained were then transfected into LM2 cells and their malignant phenotype was tested in vitro and in vivo, and compared with that of the untransfected LM2 cells.Results Three human DNA fragments of 700, 500 and 300 bp were isolated. DNA sequencing revealed that the 700bp fragment does not show homology with hitherto reported genes and was accepted by the Genbank (pt712 U67835). In vitro proliferation and colony formation in soft agar of the 700 bp fragment-transfected LM2 cells were significantly inhibited as compared to the untransfected LM2 cells. Upon subcutaneous inoculation to syngeneic T739 mice, the 700bp-transfected LM2 cells grew more slowly and smaller tumors developed compared to the untransfected ones. Moreover, lung metastasis was not found in 6 of 10 mice inoculated with the 700bp-transfected LM2 cells, while it was found in 9 of 10 mice inoculated with the untransfected LM2 cells. The difference was statistically significant (P<0.001). The frequency of lymph node metastasis was also statistically different between the 2 groups of mice.Conclusion The newly isolated 700bp human DNA fragment may be a metastasis suppressor gene of malignant tumor.

Applications and roles of the CRISPR system in genome editing of plants

Genome editing is a valuable tool to target specific DNA sequences for mutagenesis in the genomes of microbes, plants, and animals. Although different genome editing technologies are available, the clustered regularly interspaced short palindromic repeats/Cas9 （CRISPR/ Cas9） system, which utilizes engineered endonucleases to generate a double-stranded DNA break （DSB） in the target DNA region and subsequently stimulates site-specific mutagenesis through DNA repair machineries, is emerging as a powerful genome editing tool for elucidating mecha- nisms of protection from plant viruses, plant disease resistance, and gene functions in basic and applied research. In this review, we provide an overview of recent advances in the CRISPR system associated genome editing in plants by focusing on application of this technology in model plants, crop plants, fruit plants, woody plants and grasses and discuss how genome editing associated with the CRISPR system can provide insights into genome modifications and functional genomics in plants.

Investigation on the Interface between Exons and Introns in the Genomic DNA of Arabidopsis thaliana in the Phase Space

In this study,three weight vectors L1,L2 and L3 were set.After calculating the probability of three bases in the exons or introns in the genomic DNA of Arabidopsis thaliana,64-dimensional vector P was obtained.Dot products of P vector and three weight vectors were the feature coordinates for the exons and introns in 3-dimensional phase space.The expression for the interface between the exons and the introns in the genomic DNA of Arabidopsis thaliana in 3-dimensional phase space was established,which could be used to distinguish the exons and the introns in the genomic DNA of Arabidopsis thaliana with an accuracy higher than85%in 3-dimensional phase space.

Pathogenic Effects of Cloned Genomic DNA of Porcine Circovirus-like Virus P1 on Neonatal Mice via Different Inoculation Routes

[Objective] The paper was to explore the pathogenicity of cloned genomic DNA of porcine circovirus-like virus Pl to neonatal mice via different inoculation routes （brain, liver and muscle）. [Method] Cloned genomic DNA of P1 was inoculated to neonatal mice via different routes of brain, liver and muscle. Tissues of heart, liver, spleen, lung, kidney and brain were taken from neonatal mice at 7, 14 and 21 d post inoculation, re- spectively. Pl in various tissues were qualitatively and quantitatively detected by using ordinary PCR and quantitative real-time PCR. Meanwhile, histopathological changes were analyzed. [Result] Pl was detected in neonatal mice inoculated through three different routes. The viral load of tis- sues at 7 d post inoculation was significantly higher than those at 14 and 21 d post inoculation. Moreover, muscle inoculation led to the highest viral load in all tissues of neonatal mice. [Conclusion] Pl infection caused different degrees of pathological damage to heart, liver, lung, kidney and brain in neonatal mice.

Pathogenicity of diatraea saccharalis Densovirus to Host Insets and Characterization of its Viral Genome

Diatraea saccharalis densovirus (DsDNV ) 的致病力在它的主人幼虫上被测试。结果证明直到在接种以后的 4 天，没有幼虫死亡被观察，感染的幼虫开始从第四天展出感染症状。在 5 天感染以后，感染的幼虫的累积死亡显著地增加了并且而分别地，控制组的仅仅在感染的一样的时期以后是10%和20%，在 21 天感染以后在 12 天和100%以后到达了60%，建议感染的幼虫组的高死亡由于 DsDNV 的高致病力。DsDNA 的尺寸被病毒的 DNA 分子的电子显微镜学可视化决定，土著人和 endonuclease 的胶化电气泳动消化了 DNA 碎片。本国的 DsDNA 的全部的长度是大约 5.95 kb。DsDNV DNA 与 16 限制酶被消化，那些酶的一张限制地图与 41 个限制地点被构造。Junonia coenia densovirus (JcDNV ) 和街郎 mellonella densovirus (GmDNV ) 的染色体的有那些的 DsDNV 染色体的限制地图的比较显示三个 densovirus 染色体被发现分享许多相同限制地点。因此，大多数下列 endonucleases 欺骗 H 的限制地点我， Hha 我， Xba 我， Cla 我，毒蛇 700， Spe 我， Nco 我和 Bcl 我，被发现在三个 densovirus 染色体之中被保存。在染色体的两结束印射的对称的劈开地点建议了其尺寸被估计是大约 500 bp 的转换终端重复(国际互联网广播台) 的存在。类似的染色体尺寸，几乎相同的限制地点和为这三 densoviruses 的大约 500 bp 的一个国际互联网广播台的存在建议他们属于 ambisense densoviruses 的一样的组。钥匙词致病力 - Densovirus - Diatraea saccharalis - Genomic DNA - 限制地图 CLC 数字 S852.65 基础条款：中国(30670081 ) 的国家自然科学基础；由 IRD 同意了(研究所 de 精选倒 developpement )

Remarkably different results between two studies from North America on genomic mutations and sensitivity to DNA demethylating agents for myelodysplastic syndromes

Sekeres et al. （1） conducted a multicenter randomized, controlled trial to compare whether azacitidine-based combinations with lenalidomide or vorinostat produce superior overall response rates to azacitidine in the treatment of myelodysplastic syndromes （MDS）. In that trial, 224 patients with higher-risk MDS and 53 with chronic myelomonocytic leukemia （CMML） were enrolled and randomly assigned to the ＂azacitidine＂ group, ＂azacitidine plus lenalidomide＂ group or ＂azacitidine plus vorinostat＂ group. The researchers found that patients with MDS treated with azacitidine-based combinations had similar response rate to azacitidine monotherapy. Using genomic mutation analysis, they found that the overall response rate to azacitidine-based treatment was higher for patients with mutations in DNMT3A and lower for those with mutations in SRSF2. Whereas in another study, Welch et al. enrolled 26 patients with MDS and 90 with acute myeloid leukemia （AML） who were treated with decitabine, and they found that patients with TP53 mutations had a higher response rate, but not those with DNMT3A mutations （2）. We propose that this big discrepancy in the conclusions between the two studies might have been caused by the presence of many co-interacting factors, e.g. study aims, DNA demethylating agents, treatment protocols, and patient sources.

Genomics of pancreatic ductal adenocarcinoma

Pancreatic cancer is one of the worst prognostic cancers because of the late diagnosis and the absence of effective treatment. Within all subtypes of this disease, ductal adenocarcinoma has the shortest survival time. In recent years,global genomics profiling allowed the identification of hundreds of genes that are perturbed in pancreatic cancer. The integration of different omics sources in the study of pancreatic cancer has revealed several molecular mechanisms, indicating the complex history of its development. However, validation of these genes as biomarkers for early diagnosis, prognosis or treatment efficacy is still incomplete but should lead to new approaches for the treatment of the disease in the future.

Effective Isolation of Retrotransposons and Repetitive DNA Families from the Wheat Genome

New classes of repetitive DNA elements were effectively identified by isolating small fragments of the elements from the wheat genome. A wheat A genome library was constructed from Triticum monococcum by degenerate cleavage with EcoO1091, the recognition sites of which consisted of 5＇-PuGGNCCPy-3＇ multi-sequences. Three novel repetitive sequences pTm6, pTm69 and pTm58 derived from the A genome were screened and tested for high copy number using a blotting approach, pTm6 showed identity with integrase domains of the barley Tyl-Copia-retrotransposon BARE-1 and pTm58 showed similarity to the barley Ty3-gypsy-like retrotransposon Romani. pTm69, however, constituted a tandem array with useful genomic specificities, but did not share any identity with known repetitive elements. This study also sought to isolate wheat D-genome-specific repetitive elements regardless of the level of methylation, by genomic subtraction. Total genomic DNA of Aegilops tauschii was cleaved into short fragments with a methylation-insensitive 4 bp cutter, Mbol, and then common DNA sequences between Ae. tauschii and Triticum turgidum were subtracted by annealing with excess T. turgidum genomic DNA. The D genome repetitive sequence pAt1 was isolated and used to identify an additional novel repetitive sequence family from wheat bacterial artificial chromosomes with a size range of 1 395-1 850 bp. The methods successfully led pathfinding of two unique repetitive families.

Molecular Identification of Co-Existence of Carbapenemase and Extended-Spectrum <i>β</i>-Lactamase Genes in <i>Klebsiella pneumoniae</i>Clinical Isolates, and Their Phylogenetic Patterns in Kenya

The increasing incidence of multidrug-resistant Klebsiella pneumoniae strains has become a serious global healthcare problem. Additionally, the carriage of both extended-spectrum ß-lactamase and carbapenemase genes on plasmid and genomic DNA in K. pneumoniae clinical isolates has not been documented in Kenya. This study aimed to assess the presence of extended spectrum β-lactamase (ESBL) and carbapenemase genes on genomic and plasmid DNA in K. pneumoniae, and classify these super-bug clinical isolates based on their phylogenetic patterns. The identification of Klebsiella-like clinical isolates (n = 20) collected from Kenyatta National Hospital in Nairobi was performed using API 20E Kit. Screening and confirmation for ESBL and carbapenemase phenotypes were conducted using Kirby-Bauer disk diffusion susceptibility test protocol. Conventional PCR technique was used to characterize ESBL and carbapenemase resistant genes on both genomic and plasmid DNA. Subsequently, 16S rRNA gene amplification and sequencing were performed. The 16S rRNA gene contiguous sequences of the bacterial isolates were analyzed using the ChromasPro. The gene sequence was compared with the sequences in GenBank database, using the BLAST program of NCBI to obtain the nearest phylogenetic neighbours from the databases. Then, the sequences of MDR K. pneumoniae and its relatives were aligned using ClustalW. The evolutionary history was inferred by using the maximum likelihood algorithm in MEGA MX. The phenotypic data of antibiotic susceptibility testing revealed that 2/20 (10%) clinical isolates were resistant both to imipenem and meropenem and producers of carbapenemase. These isolates were carbapenemase producers but not extended β-lactamases. However, 3/20 (15%) isolates that co-harboured blaNDM-1, blaIMP, blaTEM, and bla-OXA were identified during genotypic analysis. The positive control used separately yielded the expected band sizes for blaIMP (275 bp), blaOXA-48 (438 bp), and BlaKPC (798). The phylogenetic analysis showed the dual ESBL and carbapenemase producing Klebsiella pneumoniae could be classified as K. pneumoniae strain DSM 30104 and K. pneumonia subsp. pneumoniae strain GMH1080. This study confirmed the co-existence of ESBL and carbapenemase genes in Klebsiella pneumoniae on both bacterial genomic and Plasmid DNA, and demonstrated that the isolates are evolutionarily distinct. These findings raise a concern about the genotypic diversity of antibiotic resistance genes in bacterial isolates and their location. We, therefore, recommend an alternative management approach to combat these MDR bacterial isolates as well as frequent molecular surveillance programs to support antimicrobial stewardship.

The genome basis and whole-genome patterns of DNA variation of a major oil crop-oil palm Dura

Subject Code:C01The United Nations estimates that world population will increase to 11.2billion in the year 2100.Vegetative oil that serves as one of the major energy resources is essential to feeding human beings.Oil palm(Elaeis guineensis Jacq,Elaeis from ancient Greek,meaning'oil')produces more than 13times the yield of oil/year/hectare of soybean,one major human annual oil crop.In consequence,it represents a

DNA Polymorphism Among Yewei B, V20B, and Oryza minuta J. S. Presl. ex C. B. Presl.

The new cytoplasmic male sterile （CMS） line Yewei A and its maintainer line Yewei B, with better agronomic characteristics, have been developed from a mutant of V20B （a rice maintainer line） through transformation of genomic DNA of wild rice （Oryza minuta J. S. Presl. ex C. B. Presl.）. Analysis of molecular markers, DNA sequences, and Southern blot revealed that high DNA polymorphism exists between the mutant and its receptor, indicating that the special DNA fragment from O. minuta may be integrated into the genome of Yewei B. Therefore, transformation of genomic DNA from distant relatives to the plant of a target receptor may open an avenue for creating a new rice germplasm.

Diversity Suppression-Subtractive Hybridization Array for Profiling Genomic DNA Polymorphisms

Genomlc DNA polymorphlsms are very useful for tracing genetic traits end studying biological diversity among species. Here, we present a method we call the ＂diversity suppresslon-subtractlve hybridization array＂ for effectively profiling genomlc DNA polymorphisms. The method first obtains the subtracted gDNA fragments between any two species by suppression subtraction hybridization （SSH） to establish e subtracted gDNA library, from which diversity SSH arrays are created with the selected subtracted clones. The diversity SSH array hybridizes with the DIG-labeled genomlc DNA of the organism to be assayed. Six closely related Dendrobium species were studied as model samples. Four Dendrobium species as testers were used to perform SSH. A total of 617 subtracted positive clones were obtained from four Dendrobium species, and the average ratio of positive clones was 80.3%. We demonstrated that the average percentage of polymorphlc fragments of palrwlse comparisons of four Dendrobium species was up to 42.4%. A dendrogram of the relatedness of six Dendrobium species was produced according to their polymorphic profiles. The results revealed that the diversity SSH array Is a highly effective platform for profiling genomlc DNA polymorphlsms and dendrograms.

Characterization of Episomal Replication of Bovine Papillomavirus Type 1 DNA in Long-Term Virion-Infected Saccharomyces Cerevisiae Culture

We have previously reported that bovine papillomavirus type 1(BPV-1) DNA can replicate its genome and produce infectious virus-like particles in short term virion-infected S. cerevisiae(budding yeast) cultures(Zhao and Frazer 2002,Journal of Virology, 76:3359–64 and 76:12265–73). Here, we report the episomal replications of BPV-1 DNA in long term virion-infected S. cerevisiae culture up to 108 days. Episomal replications of the BPV-1 DNA could be divided into three patterns at three stages, early active replication(day 3–16), middle weak replication(day 23–34/45) and late stable replication(day 45–82). Two-dimensional gel electrophoresis analysis and Southern blot hybridization have revealed further that multiple replication intermediates of BPV-1 DNA including linear form, stranded DNA, monomers and higher oligomers were detected in the virion-infected yeast cells over the time course. Higher oligomers shown as covalently closed circular DNAs(cccDNAs) are the most important replication intermediates that serve as the main nuclear transcription template for producing all viral RNAs in the viral life cycle. In this study, the cccDNAs were generated at the early active replication stage with the highest frequencies and then at late stable replication, but they appeared to be suppressed at the middle weak replication. Our data provided a novel insight that BPV-1 genomic DNA could replicate episomally for the long period and produce the key replication intermediates cccDNAs in S. cerevisiae system.

Character of cell-free genomic DNA in embryo culture medium and the prospect of its clinical application in preimplantation genetic testing

There is increasing evidence that cell-free DNA (cfDNA) in spent culture media (SCM) can be amplified for genetic testing. Therefore, this paper reviews the characteristics of cfDNA, including its fragment size, amount, origin, as well as some factors affecting the success rate of its amplification, together to provide researchers with a more comprehensive perspective on embryonic cfDNA. The origin of cfDNA in SCM is complicated and poses challenges to the interpretation of genetic test results. Advanced molecular techniques should distinguish between embryonic and contaminated DNA to maximize the success rate of amplification and analysis. Recent data showed that the type of culture medium, assisted hatching or not, the type of amplification kit, and fresh or thawed embryos were not related to the success rate of amplification, but the length of culture time might affect the success rate. The longer culture time, the more cfDNA is available in the SCM. Then we focused on the concordance between trophectoderm (TE), inner cell mass, whole embryo, and embryonic cfDNA. Despite successful amplification, the concordance between TE and embryonic cfDNA was low. In summary, non-invasive genetic testing using SCM could represent a major advance in future single embryo selection, however, contamination and timing for media collection are key factors affecting the results, and current non-invasive cfDNA testing should not be directly applied to clinical practice. Further research is needed to improve the methods used for testing techniques and genetic analysis to achieve greater accuracy and trace its origins before it can be used in the clinics.

DNA End Resection:Facts and Mechanisms

DNA double-strand breaks（DSBs）,which arise following exposure to a number of endogenous and exogenous agents,can be repaired by either the homologous recombination（HR）or non-homologous end-joining（NHEJ） pathways in eukaryotic cells.A vital step in HR repair is DNA end resection,which generates a long 30single-stranded DNA（ss DNA） tail that can invade the homologous DNA strand.The generation of 30 ss DNA is not only essential for HR repair,but also promotes activation of the ataxia telangiectasia and Rad3-related protein（ATR）.Multiple factors,including the MRN/X complex,C-terminal-binding protein interacting protein（Ct IP）/Sae2,exonuclease 1（EXO1）,Bloom syndrome protein（BLM）/Sgs1,DNA2 nuclease/helicase,and several chromatin remodelers,cooperate to complete the process of end resection.Here we review the basic machinery involved in DNA end resection in eukaryotic cells.

Maintenance of Genome Stability

It was ever thought that genomic information is transmitted faithfully from generation to generation. But our current knowledge does not indicate that it is the case. For example, genomic variations can be generated from DNA replication infidelity and unequal chromosome segregation. Natural decay of DNA molecules is also a fundamental source of changing genomic information. In addition, cellular and organismal exposure to exogenous genotoxic agents such as ultraviolet （UV） light, oxidative stress, chemical mutagens, and radiation can lead to a variety of modifications on DNA constituents, resulting in genome alterations. Fortunately, cells have evolved several response systems to tackle numerous DNA lesions in order to maintain their genome integrity. Among them, check- point control is probably the most well-known one. For exam- ple, checkpoint responds to replication stress, replication fork stalling, double-strand DNA breaks, and various other types of DNA lesions. Increasing experimental evidence indicates that genomic instability is probably the fundamental reason for carcinogenesis. Genomic instability is also found to be a main etiological factor of neurodegenerative diseases, aging, immunodeficiency, etc. Thus, to understand how cells regulate to maintain their genomic stability is of fundamental importance.

Estimation of Nuclear DNA Content in Tannin-rich Medicinal Plant Cornus officinalis by Flow Cytometry

Objective The amount of nuclear DNA（C-value）is a key biodiversity character that provides strong unifying elements in revealing the phylogenetic regularity and relationship between genome size and functional traits for plant resource.The estimation of C-values could primarily extend our knowledge on the genetic background and genome diversity for medicinal plants,and thereby the variation of pharmacological constituents and phylogenetic mechanism of medicinal plant taxa will be revealed.However,a large number of medicinal plants（e.g.Cornus officinalis）typically contain a series of secondary metabolites,especially tannic acid,which would significantly affect the estimation of DNA content by flow cytometry（FCM）.Methodological discussions and improvement need to be made to solve this problem.Methods Two isolation buffers LB01 and Otto 1 were selected to prepare nuclear suspension with additional treatments of pre-soaking and centrifugation combination of gradient centrifugal force and duration.The best isolation and estimation methods were determined by FCM measurement in C.officinalis.Results The dry leaves were pre-soaked in Otto I buffer for 15 min and the Otto I nuclear suspension was centrifugated at 1.0×103 g for 2 min.The results showed that debris and nuclei were better separated and the scatterplots of good quality were obtained with low coefficient of variation（CV）.Contrarily,the nuclear DNA content of C.officinalis could not be accurately estimated for nuclei extracted by LB01 buffer.Finally,2C-value and genome size of C.officinalis were first estimated as 5.92 pg and 2893 Mbp,respectively.Conclusion The new methods proposed here are able to accurately estimate DNA content of C.officinalis,which provides valuable references for the estimation of genome size in other tannin-rich medicinal plants.