Analysis of drought tolerance and genetic and epigenetic variations in a somatic hybrid between Ipomoea batatas (L.) Lam. and I. triloba L.

The somatic hybrid KT1 was previously obtained from protoplast fusion between sweetpotato （Ipomoea batatas （L.） Lam.） cv. Kokei No. 14 and its wild relative I. triloba L. However, its genetic and epigenetic variations have not been investigated. This study showed that KT1 exhibited significantly higher drought tolerance compared to the cultivated parent Kokei No. 14. The content of proline and activities of superoxide dismutase （SOD） and photosynthesis were significantly increased, while malonaldehyde （MDA） content was significantly decreased compared to Kokei No. 14 under drought stress. KT1 also showed higher expression level of well-known drought stress-responsive genes compared to Kokei No. 14 under drought stress. Amplified fragment length polymorphism （AFLP） and methylation-sensitive amplified polymorphism （MSAP） analyses indicated that KT1 had AFLP and MSAP band patterns consisting of both parent specific bands and changed bands. Fur- ther analysis demonstrated that in KT1. the proportions of Kokei No. 14 specific genome components and methylation sites were much greater than those of I. triloba. KT1 had the same chloroplast and mitochondrial genomes as Kokei No. 14. These results will aid in developing the useful genes ofI. triloba and understanding the evolution and phylogeny of the cultivated sweetpotato.

Genetic variations in the SMAD4 gene and gastric cancer susceptibility

AIM:To explore the association between mothers against decapentaplegic homolog 4 (SMAD4) gene polymorphisms and gastric cancer risk.METHODS:Five tagging single nucleotide polymor-phisms (tSNPs) in the SMAD4 gene were selected and genotyped in 322 gastric cancer cases and 351 cancerfree controls in a Chinese population by using the polymerase chain reactionrestriction fragment length polymorphism method.Immunohistochemistry was used to examine SMAD4 protein expression in 10 normal gastric tissues adjacent to tumors.RESULTS:In the single-locus analysis,two significantly decreased risk polymorphisms for gastric cancer were observed:the SNP3 rs17663887 TC genotype (adjusted odds ratio=0.38,95% confidence interval:0.21-0.71),compared with the wild-type TT genotype and the SNP5 rs12456284 GG genotype (0.31,0.16-0.60),and with the wild-type AA genotype.In the combined analyses of these two tSNPs,the combined genotypes with 2-3 protective alleles (SNP3 C and SNP5 G allele) had a significantly decreased risk of gastric cancer (0.28,0.16-0.49) than those with 0-1 protective allele.Furthermore,individuals with 0-1 protective allele had significantly decreased SMAD4 protein expression levels in the norma tissues adjacent to tumors than those with 2-3 protective alleles (P=0.025).CONCLUSION:These results suggest that genetic variants in the SMAD4 gene play a protective role in gastric cancer in a Chinese population.

Association of genetic variations of the prostasin gene with essential hypertension in the Xinjiang Kazakh population

Background Transgenic overexpression of human prostasin in rats disturbs salt balance and causes hypertension. We investigated whether genetic variations in prostasin were implicated in hypertension or related phenotypes in the Xinjiang Kazakh population.Methods We sequenced all exons and the promoter regions of the prostasin gene in 94 hypertensive individuals, and the genotype identification was performed by the TaqMan polymerase chain reaction method. Case-control studies were conducted in 938 Kazakh subjects.Results E342K and 2827G＞A, which are novel variants, were successfully genotyped in the general Xinjiang Kazakh population with a sample size of 938 individuals （406 men and 532 women）. Only one hypertensive patient was identified with the E342K mutation. No significant association was observed between 2827G＞A and hypertension. However,quantitative traits of hypertensive intermediate phenotypes were significantly associated with the A allele; P=-0.041 and 0.034 for body mass index （BMI） in the additive and recessive models, P=0.042 and 0.018 for OGTT-2h glucose in the additive and recessive models, P=0.031 for IRT-3h insulin in the recessive model, and P=0.038 for serum potassium in the dominant model.Conclusions This study does not provide evidence of a major role of prostasin variation in blood pressure modulation.However, association of prostasin polymorphisms with hypertension and metabolic effects can be observed in our population. Further investigation is warranted to clarify the relevance of prostasin polymorphisms to blood pressure regulation.

RAD-sequencing improves the genetic characterization of a threatened tree peony(Paeonia ludlowii)endemic to China:Implications for conservation

Compared with traditional genetic markers,genomic approaches have proved valuable to the conservation of endangered species.Paeonia ludlowii having rarely and pure yellow flowers,is one of the world’s most famous tree peonies.However,only several wild populations remain in the Yarlung Zangbo Valley(Nyingchi and Shannan regions,Xizang)in China due to increasing anthropogenic impact on the natural habitats.We used genome-wide single nucleotide polymorphisms to elucidate the spatial pattern of genetic variation,population structure and demographic history of P.ludlowii from the fragmented region comprising the entire range of this species,aiming to provide a basis for conserving the genetic resources of this species.Unlike genetic uniformity among populations revealed in previous studies,we found low but varied levels of intra-population genetic diversity,in which lower genetic diversity was detected in the population in Shannan region compared to those in Nyingzhi region.These spatial patterns may be likely associated with different population sizes caused by micro-environment differences in these two regions.Additionally,low genetic differentiation among populations(Fst=0.0037)were detected at the species level.This line of evidence,combined with the result of significant genetic differentiation between the two closest populations and lack of isolation by distance,suggested that shared ancestry among now remnant populations rather than contemporary genetic connectivity resulted in subtle population structure.Demographic inference suggested that P.ludlowii probably experienced a temporal history of sharp population decline during the period of Last Glacial Maximum,and a subsequent bottleneck event resulting from prehistoric human activities on the Qinghai-Tibet Plateau.All these events,together with current habitat fragment and excavation might contribute to the endangered status of P.ludlowii.Our study improved the genetic characterization of the endangered tree peony(P.ludlowii)in China,and these genetic inferences should be considered when making different in situ and ex situ conservation actions for P.ludlowii in this evolutionary hotspot region.

Genome-wide association studies reveal the genetic basis of amino acid content variation in tea plants

Tea is one of the most popular non-alcoholic beverages in the world,and free amino acids,especially theanine,make a major contribution to the umami taste of tea.However,the genetic basis of the variation in amino acid content in tea plants remains largely unknown.Here,we measured the free amino acid content in fresh leaves of 174 tea accessions over two years using a targeted metabolomics approach and obtained genotype data via RNA sequencing.Genome-wide association studies were conducted to investigate loci affecting the content of free amino acids.A total of 69 quantitative trait loci(–log10(P-value)>5)were identified.Functional annotation revealed that branched-chain amino acid aminotransferase,glutamine synthetase,nitrate transporter,and glutamate decarboxylase might be important for amino acid metabolism.Two significant loci,glutamine synthetase(Glu1,P=3.71×10^(−4);Arg1,P=4.61×10^(−5))and branched-chain amino acid aminotransferase(Val1,P=4.67×10^(−5);I_Leu1,P=3.56×10^(−6)),were identified,respectively.Based on the genotyping result,two alleles of CsGS(CsGS-L and CsGS-H)and CsBCAT(CsBCAT-L and CsBCAT-H)were selected to perform function verification.Overexpression of CsGS-L and CsGS-H enhanced the contents of glutamate and arginine in transgenic plants,and overexpression of CsBCAT-L and CsBCAT-H promoted the accumulation of valine,isoleucine and leucine.Enzyme activity assay uncovered that SNP1054 is important for CsGS catalyzing glutamate into glutamine.Furthermore,CsGS-L and CsGS-H differentially regulated the accumulation of glutamine,and CsBCAT-L and CsBCAT-H differentially regulated the accumulation of branched-chain amino acids.In summary,the findings in our study would provide new insights into the genetic basis of amino acids contents variation in tea plants and facilitate the identification of elite genes to enhance amino acids content.

Genetic polymorphisms in genes regulating cell death and prognosis of patients with rectal cancer receiving postoperative chemoradiotherapy

Objective:The identification of biomarkers for predicting chemoradiotherapy efficacy is essential to optimize personalized treatment.This study determined the effects of genetic variations in genes involved in apoptosis,pyroptosis,and ferroptosis on the prognosis of patients with locally advanced rectal cancer receiving postoperative chemoradiotherapy(CRT).Methods:The Sequenom MassARRAY was used to detect 217 genetic variations in 40 genes from 300 patients with rectal cancer who received postoperative CRT.The associations between genetic variations and overall survival(OS)were evaluated using hazard ratios(HRs)and 95%confidence intervals(CIs)computed using a Cox proportional regression model.Functional experiments were performed to determine the functions of the arachidonate 5-lipoxygenase(ALOX5)gene and the ALOX5 rs702365 variant.Results:We detected 16 genetic polymorphisms in CASP3,CASP7,TRAILR2,GSDME,CASP4,HO-1,ALOX5,GPX4,and NRF2 that were significantly associated with OS in the additive model(P<0.05).There was a substantial cumulative effect of three genetic polymorphisms(CASP4 rs571407,ALOX5 rs2242332,and HO-1 rs17883419)on OS.Genetic variations in the CASP4 and ALOX5 gene haplotypes were associated with a higher OS.We demonstrated,for the first time,that rs702365[G]>[C]represses ALOX5 transcription and corollary experiments suggested that ALOX5 may promote colon cancer cell growth by mediating an inflammatory response.Conclusions:Polymorphisms in genes regulating cell death may play essential roles in the prognosis of patients with rectal cancer who are treated with postoperative CRT and may serve as potential genetic biomarkers for individualized treatment.

APOBEC3G Role on HIV Infection in Africa: A Systematic Review

The highly active antiretroviral treatment (HAART) has allowed people living with HIV to live longer with a better quality of life. However, toxicity and the emergence of drug resistance arise from HAART use. Therefore, new antiretroviral therapy is needed since no cure or vaccine is available against HIV. Virus-host interaction has been proven to be important in the last decade. Host factors such as the C-C chemokine receptor type 5 (CCR5), a receptor used by HIV to penetrate host cells, have led to the discovery of the Maraviroc, which is an antiretroviral medication used in the United States. In contrast, other factors like C-X-C Motif Chemokine Receptor 4 (CXCR4) and the Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3G (APOBEC3G), a potent host defense factor against HIV, is under investigation. APOBEC3G antiviral activity remains a possible therapeutic target against HIV. This systematic review aimed to synthesize the available evidence on the role of APOBEC3G polymorphisms and their expression on HIV infection disease progression in Africa. We used Web of Science, PubMed, Embase, and Google Scholar and searched for relevant publications in French or English reporting on APOBEC3G polymorphisms association with HIV infection in African populations from January 2009 to May 2023. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyzes) was used to process for reporting systematic review. Fifteen studies were included, of which seven were on APOBEC3G polymorphisms and eight were on APOBEC3G expression. Among the APOBEC3G polymorphisms, the most studied was H186R or rs8177832. The average of the minor allele frequency of H186R of APOBEC3G available for the studies included in this study was 0.29 with a 95% CI (0.172;0.401) and varied from 0.108 reported in Uganda to 0.47 recorded from Burkina Faso. The polymorphism H186R was not associated with HIV status in Southern Africa. However, the referent allele of H186R was protective against HIV infection in Western Central Africa, while in West Africa, it was the minor allele (G) of H186R which was protective against HIV. This review warrants a need to increase research on APOBEC3G, from its variants to its hypermutations on the continent with an essential variety of HIV-1 subtypes, to impact the research on A3G-based anti-HIV strategies.

Assessment of Genetic Variation in Soybean (<i>Glycine max</i>) Accessions from International Gene Pools Using RAPD Markers: Comparison with the ISSR System

Soybean (Glycine max) is one of the most important crops in the world in terms of total production and usage. It is also among the least diverse species. The main objectives of the present study were to 1) assess the level of genetic variation among soybean (G. max) accessions from different countries using Random Amplified Polymorphic DNA (RAPD) markers and 2) compare Inter Simple Sequence Repeats (ISSR) and RAPD marker systems in detecting polymorphic loci in soybeans (G. max). Genomic DNAs from 108 soybeans (G. max) accessions from 11 different gene pools were analyzed using several ISSR and RAPD primers. The average level of polymorphic loci detected with the RAPD primers was 35%. The soybean accessions from the China, Netherlands, and Canada gene pools were the least genetically variable with 25%, 26%, and 30% of polymorphic loci, respectively. Accessions from Hungary (43%) and France (48%) showed the highest level of polymorphism based on the RAPD analysis. Overall, RAPD data revealed that the accessions from different countries are closely related with 64% genetic distance values below 0.40. The levels of polymorphic loci detected with the RAPD and ISSR marker systems were in general moderate and similar even if they target different regions of the genome. A combination of different marker systems that include RAPD/ISSR, microsatellites (SSR), and SNPs should provide the most accurate information on genetic variation of soybean (G. max) accessions.

Genetic variation of Laminaria japonica (Phaeophyta) populations in China as revealed by RAPD markers

For the population genetics analysis of the naturally grown brown seaweed Laminaria japonica （Laminariales,Phaeophyta） sampled from Dalian,Yantai,Weihai,Rongcheng and Qingdao in China,ten primers were employed to produce 88 bands as revealed by randomly amplified polymorphic DNA （RAPD） markers,and all these bands were polymorphic.According to these band patterns,there were 94 distinct phenotypes occurred in 100 samples indicating the high heterozygosity of this kelp.Dalian population samples showed the highest percentage of polymorphism （71.67%）,and also the higher diversity estimated on the basis of the Shannon’s index （8.498）,suggesting that this population could be chosen as the best resource for genetic breeding.The highest diversity of Yantai population possibly resulted from the introduction of L.longissima used for interspecific cross breeding with L.japonica cultivated in China.From Dalian southwards to Qingdao,the genetic variation of the five populations became less with a decrease in latitude,possibly due to the natural selection especially of high temperature.The genetic distance （Φ ST values） of the five populations was a little significantly correlated with the geographical distance （r=0.496） at P =0.05 by Mantel’s test.Weihai,Rongcheng and Yantai populations were closely grouped genetically together by Neighbor-joining cluster analysis probably in that the dispersal of the kelp by propagules more easily occurring in the range of relatively short distance.The analysis of molecular variance （AMOVA） also demonstrated that the relatively higher variation occurred among populations （71.49%） at an extremely significant level （P 0.000 1）.All these evidence showed that there was a relatively distinct genetic differentiation among the sampled kelp populations,and L.japonica grown in China was also rather heterozygous in heredity.

Genetic Variation in Triticum turgidum L. ssp. turgidum Landraces from China Assessed by EST-SSR Markers

It was helpful for the wheat improvement to evaluate the genetic resources of Triticum turgidum L. ssp. turgidum landraces. In this study, 68 turgidum landraces accessions, belonging to four geographic populations in China, were investigated by using EST-SSR markers. A total of 63 alleles were detected on 22 EST-SSR loci, and the number of alleles on each locus ranged from 1 to 5, with an average of 2.9. The results of the analysis of molecular variance （AMOVA） indicated that 92.5% of the total variations was attributed to the genetic variations within population, whereas only 7.5% variations among populations. Although the four populations had similar genetic diversity parameters, Sichuan population was yet distinguished from other populations when comparing the population samples in pairs. Significant correlations were detected by the statistic analysis among six genetic diversity parameters among each other. The selection difference between heterozygosty and homozygosty was also observed among different EST-SSR locus. The genetic similarity （GS） ranged from 0.18 to 0.98, with the mean of 0.72, and all accessions could be clustered into 7 groups. The dendrogram suggested that the genetic relationships among turgidum accessions evaluated by EST-SSR markers were unrelated to their geographic distributions. These results implied that turgidum landraces from China had the unique characters of genetic diversity.

Advances in salinity tolerance of soybean: Genetic diversity, heredity, and gene identification contribute to improving salinity tolerance

Salt stress is one of the major abiotic stresses affecting soybean growth. Genetic improvement for salt tolerance is an effective way to protect soybean yield under salt stress conditions. Successful improvement of salt tolerance in soybean relies on identifying genetic variation that confers tolerance in soybean germplasm and subsequently incorporating these genetic resources into cultivars. In this review, we summarize the progress in genetic diversity and genetics of salt tolerance in soybean, which includes identifying genetic diversity for salt tolerant germplasm; mapping QTLs conferring salt tolerance; map-based cloning; and conducting genome-wide association study（GWAS） analysis in soybean. Future research avenues are also discussed, including high throughput phenotyping technology, the CRISPR/Cas9 Genome-Editing System, and genomic selection technology for molecular breeding of salt tolerance.

Genetic variation and division of Pinus sylvestris provenances by ISSR markers

Inter Simple Sequence Repeat （ISSR） was used to detect genetic variation among nine provenances, including 135 individuals. A total of 108 loci were amplified using 10 random primers. The differentiation of the percentage of polymorphic bands （PPB） among different provenances was evident, ranging from 27% to 54%. of which Honghuaerji provenance had the highest PPB and Kalunshan provenance had the lowest PPB. Shannon＇s Information index （1） at species level was 0.1581 and Nei＇s gene diversity （h） was 0.2393. Coefficient of gene differentiation （Gsr） calculated by Popgene was 0.3965, these results indicated that majority of genetic variation （60.35%） was found within provenances. According to dendrogram among pinus sylvestriv provenances, nine provenances were divided into two provenance areas. namely Daxing＇an and Xiaoxing＇an Mountains provenance area and Hulunbeier provenance area.

Genetic Variation Analysis on the Whole Genomic Sequence of a H9N2 Subtype Avian Influenza Virus Isolate

A Objective3 This study was to understand the genetic variation characters of the H9N2 subtype avian influenza virus isolate （A/Chicken/ Hebei/WD/98, abbreviated as WD98） by comparing with other reference strains. I-Method3 Eight complete genes were amplified by RT-PCR and sequenced. The homology and genetic evolution relationship were analyzed between these sequences and that of the seven reference strains. [Result] The whole genomic sequence of WD98 strain was 91.1% -95.8% homologous to that of seven reference strains tested. This isolate shared the highest homology （95.8%） to D/HK/Y280/97 and the lowest homology （91.1% ） to C/Pak/2/99. The HA cleavage site of the WD98 strain was R-S-S-R G, and the 226th amino acid at receptor-binding site was Gin. [ Condmion] WD98 strain belongs to mildly pathogenic avian in- fluenza virus and may not infect human. The genetic relationship is the closest between A/Chicken/Hebei/wD/98 and A/duck/HongKong/Y280/ 97, both of which belong to the sub-line of A/Chicken/Beijing/1/94 in Eurasian line. And A/Chicken/Hebei/WD/98 and A/Chicken/Beijing/1/94 are genetically distant within the same sub-line.

Genetic Analysis of Four Populations of Redlip Mullet(Chelon haematocheilus) Collected in China Seas

Horizontal starch gel electrophoresis was used to investigate genetic structures of four populations (Dandong, Rizhao, Ningbo and Guangzhou) of redlip mullet (Chelon haematocheilus). Fourteen loci of ten enzymes (G3PDH, IDHP, LAP, LDH, MDH, MPI, PGDH, PGM, SDH, and SOD) were identified. The proportions of polymorphic loci varied from 0.07 to 0.14. The average observed and expected heterozygosities ranged from 0.02 to 0.05 and from 0.02 to 0.04 respectively among the 4 populations. The average number of efficient alleles of each locus varied from 1.02 to 1.06. The genetic distance among populations was from 0.0004 to 0.0021. The genetic distances between Dandong, Rizhao and Ningbo populations were small, while those between Guangzhou population and other three populations were relatively high. The result indicated the possible divergence of redlip mullet between the South China Sea and the other sea areas of China due to geographic isolation.

Genetic Diversity and Genetic Changes in the Introgression Lines Derived from Oryza sativa L. Mating with O. rufipogon Griff.

The objectives of the present study were to estimate genetic diversity and genetic changes of introgression lines （ILs） which derived from cultivated rice （Oryza sativa L. cv. Xieqingzao B, XB） mating with common wild rice （O. rufipogon Griff., CWR）. The genetic data of 239 ILs were based on a total of 131 polymorphic microsatellite （SSR） markers distributed across the 12 chromosomes of rice. On average, these ILs possessed 77.1 and 14.31% homozygous bands from XB and CWR, respectively. Most of the ILs were clustered together with XB individual, which was revealed by principal coordinate analysis （PCA） and the program STRUCTURE analysis. The result from PCA demonstrated that some intermediate genotypes between XB and CWR were also found. Moreover, there were some genomic sequence changes including parental bands elimination and novel bands emergence in the ILs. The average Nei＇s gene diversity （He） was 0.296, which was higher than that of cultivated rice. It suggested that interspecific hybridization and gene introgression could broaden the base of genetic variation and lay an important foundation for rice genetic improvement. These different genotypic ILs would provide a better experimental system for understanding the evolution of rice species and the mechanism of alien gene introgression.

Biochemical genetic structure and identification of hairtail fish（Trichiurus） populations in Chinese coastal waters

A total of 472 isozyme samples and about 1 000 myogen, esterase and morphyological samples of nine spawning stocks were collected from coastal waters of Hainan, Guangdong, Fujian, Zhejiang, Jiangsu and Sbandong Provinces of China during 1976￣1992. Eleven isozymes were analysed by starch-gel and polyacrylamide-gel electrophoresis. Biochemical genetic structures of 11 isozymes were analysed and 24 loci were recorded. According to the allele frequencies of individual isozymes of each sampling stock, the mean proportion of polymorphic (P) and average heterozygosity (H) were calculated; then the genetic similarity (I) and genetic distance (D) were obtained. The results of cluster for O and D of all the samplied stocks show that the hairtail fish from Chemise coastal waters should be classified into three different sped6s (D: 0. 223￣0. 382) and eight populations (D: 0. 007￣0. 048).

Genetic structure of the invasive Colorado potato beetle Leptinotarsa decemlineata populations in China

The Colorado potato beetle(CPB),Leptinotarsa decemlineata Say,is an infamous invasive species worldwide.It was first found in Xinjiang Uygur Autonomous Region of China in 1993 and spread to Northeast China in 2013.To better understand the genetic structure and the diffusion path of their populations in China,we used nine polymorphic microsatellite loci to elucidate the genetic diversity,genetic structure and gene flow among nine CPB populations across Xinjiang and Northeast China.The results show that:(1)Two genetically separated clusters were identified by phylogenetic tree,principal coordinate analysis(PCoA)and Bayesian cluster method.Cluster one contained populations from Xinjiang,China.Cluster two contained populations from Northeast China.A genetic differentiation existed between the two clusters.(2)Three populations in Northeast China hold an obvious genetic differentiation according to the phylogenetic tree and PCoA,indicating that multiple introductions may occur in Northeast China.(3)The Altay population in Xinjiang showed a closer genetic relationship with the populations in Northeast China which may be due to the fact that they collectively originated in neighboring Russia.(4)Among all populations,Mulei and Wusu had obvious gene migrations from Tacheng,indicating that the inland populations are most likely to originate from Tacheng,Xinjiang.

Genetic Analysis on Overwintering Character of Glutinous Rice 89-1

This article discusses the overwintering ability and genetic variation of the main agronomic traits in a new germplasm resource, glutinous rice 89-1. Survival rates of overwintering axillary buds and stems were observed in different altitudes. The F1, backcross F1 and F2 populations were constructed from sexual crossing between glutinous rice 89-1 and Hongmangnuo, Fuhui 838, Minghui 63, Ce 64. The overwintering ability and genetic variation of the main agronomic traits were analyzed in different seasons. Results showed that glutinous rice 89-1 could overwinter by axillary buds in low temperatures at different altitudes. Axillary buds would ratoon in the following year. The survival rates of rice stem and axillary buds were 82.6 and 29%, respectively. The grain yields were 6 291.0 kg ha^-1 in the overwintering ratooning season, and corresponded in the main season. Genetic analysis and chi-square test showed that the overwintering ability of glutinous rice 89-1 was likely controlled by polygene, and heritabilities showed diversity in different hybrid combinations. The highest heritabilities of 1 000-grain weight and plant height were in the main crop season, whereas the lowest were in the overwintering season, and the heritabilities of grain numbers per panicle and the seed setting rate reached the highest in the ratooning season. The spikelets per panicle, the seed setting rate, the 1 000-grain weight, the plant height, and the spikelet length had nearly normal distribution in F2 populations of glutinous rice 89-1/Minghui 63, but the seed setting rate had bimodal distribution. Overwintering glutinous rice 89-1 was a useful new genetic germplasm resource.

Comparative studies on some genetic characteristics among four large yellow croaker (Pseudosciaena crocea) populations

The genetic structure was compared among four large yellow croaker （Pseudosciaena crocea） populations, an important aquaculture species in China. RAPD and ISSR results show that the genetic distances between domestic stocks and their wild counterparts are significantly larger than those between the three wild stocks. The sequence of mtDNA cyt b shows that the three wild populations share the same sequence, with differences in the four bases from the cultured stock： two transitions [57（ C-T）, 291 （G-A） ] and two transversions [66（C-G） ,223（A-C） ]. Cluster analysis reveals that the domestic stock has diverged from its parental wild stock [ Min-Yuedong （ Fujian Province-eastern Guangdong Province, China） stock]. Results demonstrate that 20 a of domestication of the Pseudosciaena crocea stock has resulted in significant genetic changes.

Genome-wide identification,evolutionary selection,and genetic variation of DNA methylation-related genes in Brassica rapa and Brassica oleracea

DNA methylation plays an important role in plant growth and development,and in regulating the activity of transposable elements(TEs).Research on DNA methylation-related(DMR)genes has been reported in Arabidopsis,but little research on DMR genes has been reported in Brassica rapa and Brassica oleracea,the genomes of which exhibit significant differences in TE content.In this study,we identified 78 and 77 DMR genes in Brassica rapa and Brassica oleracea,respectively.Detailed analysis revealed that the numbers of DMR genes in different DMR pathways varied in B.rapa and B.oleracea.The evolutionary selection pressure of DMR genes in B.rapa and B.oleracea was compared,and the DMR genes showed differential evolution between these two species.The nucleotide diversity(π)and selective sweep(Tajima’s D)revealed footprints of selection in the B.rapa and B.oleracea populations.Transcriptome analysis showed that most DMR genes exhibited similar expression characteristics in B.rapa and B.oleracea.This study dissects the evolutionary differences and genetic variations of the DMR genes in B.rapa and B.oleracea,and will provide valuable resources for future research on the divergent evolution of DNA methylation between B.rapa and B.oleracea.