Genetically-and environmentally-dependent processes drive interspecific and intraspecific divergence in the Chinese relict endemic genus Dipteronia

China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere.Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of central and south-western China allowed their persistence through the late Neogene climate fluctuations.One of these relict lineages is Dipteronia,an oligotypic tree genus with a fossil record extending to the Paleocene.Here,we investigated the genetic variability,demographic dynamics and diversification patterns of the two currently recognized Dipteronia species(Dipteronia sinensis and D.dyeriana).Molecular data were obtained from 45 populations of Dipteronia by genotyping three cpDNA regions,two single copy nuclear genes and 15 simple sequence repeat loci.The genetic study was combined with niche comparison analyses on the environmental space,ecological niche modeling,and landscape connectivity analysis.We found that the two Dipteronia species have highly diverged both in genetic and ecological terms.Despite the incipient speciation processes that can be observed in D.sinensis,the occurrence of long-term stable refugia and,particularly,a dispersal corridor along Daba Shan-west Qinling,likely ensured its genetic and ecological integrity to date.Our study will not only help us to understand how populations of Dipteronia species responded to the tectonic and climatic changes of the Cenozoic,but also provide insight into how Arcto-Tertiary relict plants in East Asia survived,evolved,and diversified.

Genetic variation and selection of 10-year-old Eucalyptus camaldulensis based on wind damage index and wood properties

Typhoons are becoming frequent and intense with ongoing climate change,threatening ecological security and healthy forest development in coastal areas.Eucalyptus of a predominant introduced species in southern China,faces significant growth challenges because of typhoon.Therefore,it is vital to investigate the variation of related traits and select superior breeding materials for genetic improvement.Variance,genetic parameter,and correlation analyses were carried out on wind damage indices and eight wood proper-ties in 88 families from 11 provenances of 10-year-old Euca-lyptus camaldulensis.The selection index equation was used for evaluating multiple traits and selecting superior prov-enances and family lines as future breeding material.The results show that all traits were highly significantly differ-ent at provenance and family levels,with the wind damage index having the highest coefficient of genetic variation.The heritability of each trait ranged from 0.48 to 0.87,with the wind damage index,lignin and hemicellulose contents,and microfibril angle having the highest heritabilities.The wind damage index had a positive genetic correlation with wood density,a negative correlation with lignin content,a negative phenotypic correlation and a negative genetic correlation with microfibril angle.Wind damage index and genetic progress in the selection of eight wood traits varied from 7.2%to 614.8%.Three provenances and 12 superior families were selected.The genetic gains of the wind damage index were 10.2%and 33.9%for provenances and families,and these may be starting material for genetic modification for wind resistance in eucalyptus and for their dissemination to typhoon-prone coastal areas of southern China.

Genetic variations of wood properties and growth characters of Ko-rean pines from different provenances

Totally 26 provenance stands of 17-year-old Korean pine were selected for investigating wood properties and growth characters in Mao抏rshan Experimental Forest Farm of Northeast Forestry University in 1999. The anatomical property indexes, including tracheid length, tracheid diameter and wall-indiameter ratio, and the physical property indexes, such as growth ring width, late wood percentage and growth ring density, were measured for wood properties. Growth character indexes, including tree height and diameter at breast height, were also measured. The analytical results showed that there exited obviously dif-ference in wood property indexes between different provenances, which is suggested that wood properties are controlled by their genetic differences. The growth character indexes of Korean pines presented significant difference and they might also be controlled by their genetic differences. Most parameters of wood properties mainly varied in the direction of longitude, but the parameters of growth characters varied in the direction of latitude.

Genetic Variation of Wild and Hatchery Populations of the Pacific Oyster Crassostrea gigas Assessed by Microsatellite Markers

Microsatellite DNA technique was used to detect the genetic variation between five hatchery populations of the Pacific oyster from China and two wild populations from Japan. Seven microsatellite loci screened in this study showed high polymorphism in both hatchery and wild populations, as observed in an average number of allele per locus （19.1-29.9） and average expected heterozygosity （0.916-0.958）. No significant difference in average allelic richness or expected heterozygosity was observed between Chinese hatchery populations and Japanese wild populations. Pairwise Fsr values and heterogeneity tests of allele frequencies showed significant genetic differentiation between all populations. According to the neighbor-joining tree constructed on the basis of the Dc distance, the seven populations fell into three groups showing a clear division between hatchery and wild populations, and between the northern and southern hatchery populations. Assignment tests correctry assigned high percentages （97%-100%） of individuals to their original populations and demonstrated the feasibility of microsatellite analysis for discrimination between populations. The information obtained in this study is useful for designing suitable management guidelines and selective breeding programs for the Pacific oyster in China.

A Preliminary Study on Genetic Variation of g E Gene of an Epidemic Pseudorabies Virus Strain and Its Pathogenicity to Piglets

[Objective] This study aimed to investigate the genetic variation of g E gene of an epidemic pseudorabies virus（PRV） strain and its pathogenicity to piglets. [Method] By serial passage in Vero cells, a PRV strain was isolated from the brain tissues of stillborn fetuses delivered by sows with suspected PRV infection and preliminarily identified by PCR. g E gene of the isolated PRV strain was amplified and sequenced for phylogenetic analysis. In addition, the pathogenicity of the isolated PRV strain to 6-week-old piglets was evaluated. [Result] A PRV strain was successfully isolated and named PRV N5 B strain, which could proliferate in Vero cells and TCID50 of the 15 thgeneration virus liquid reached 10^7.125/0.1 ml. Specific bands could be amplified by PCR. g E gene in the isolated PRV strain was 1 740 bp in length. A phylogenetic tree was constructed based on full-length g E sequences, which showed that PRV N5 B strain and PRV strains isolated since 2012 were clustered into the same independent category and shared 99.7%-100% homology of nucleotide sequences. Compared with related sequences published previously, there were insertions of three consecutive bases at two loci. Animal experiments showed that intranasal inoculation of 6-week-old piglets with 2 ml of PRV N5 B strain（10^6/0.1 ml） led to a mortality rate of 100%. [Conclusion] In this study,genetic variability of g E gene in PRV N5 B isolate and its pathogenicity to piglets were analyzed, which provided a theoretical basis for the development of new vaccines to prevent and control porcine pseudorabies.

Analysis of Genetic Variation and Population Structure of Starch Synthesis-related Genes in Indica Rice Cultivars

In this study, 34 molecular markers of starch synthesis-related genes were used to evaluate the genetic variation and population structure of 87 indica rice cultivars from different countries and regions. The results showed that a total of 80 alleles were amplified using 34 primer pairs, with an average of 2.5 alleles per locus. The allele number varied from 2 to 6 among various cultivars. Shannon＇s diversity index of molecular markers varied from 0.303 to 0.796, with an average of 0.539. Polymorphism information content （PIC） varied from 0.084 to 0.658, with an average of 0.295. The genetic similarity coefficients of 87 indica rice cultivars ranged from 0.265 to 0.990, indicating significant genetic differences of starch synthesis-related genes among different cultivars, but the variation frequency of alleles varied among different cultivars. Population structure analysis showed that these 87 indica rice cultivars were divided into three categories. Genetic differences were small within the same category but great among different categories. Moreover, indica rice cultivars with simple genetic components accounted for 39.1% and those with complex genetic background accounted for 60.9%. This study may not only provide theoretical basis for genetic improvement of rice starch quality, but also lay a solid foundation for subsequent association analysis of rice quality-related traits.

Genetic Variation Analysis of 3D Gene and Molecular Detection of Porcine Kobuvirus in 2013-2014

[Objective] This study aimed to investigate the prevalence and variation of porcine kobuvirus （PKV） in suckling piglets in China. [Method] In 2013-2014, 224 feces samples from suckling piglets with diarrhea in 27 pig farms of five provinces in China were collected to detect 3D genes of PKV with RT-PCR method; the sequences and genetic variation of 29 PKV 3D genes were analyzed. [Result] Total positive rate of PKV in feces samples from suckling piglets with diarrhea was 65.18% （146/224）; total positive rate of PKV in pig farms was 85,2% （23/27）; nucleotide sequences and the deduced amino acid sequences of 29 PKV 3D genes shared 87.0%-100% and 92.7%-100% homologies with six PKV-related 3D sequences, respectively. [Conclusion] PKV infection is prevalent in suckling piglets in China; PKV 3D genes exhibit high diversity.

Genetic Variation of the ORF5 Gene of Porcine Reproductive and Respiratory Syndrome Virus in East China during 2008-2010

[Objective] A total of 260 swine samples of dead or sick pigs collected from 7 provinces （municipalities） Jiangsu, Anhui, Shanghai, Shandong, Zhejiang, Fujian and Jiangxi of China during 2008-2010 were detected for porcine reproductive and respiratory syndrome virus （PRRSV）. And the ORF5 genes of some isolates were amplified and sequenced for understanding the molecule epidemiology and the genetic evolution of PRRSV in East China. [Method] Using RT-PCR method, PRRSV was detected by RT-PCR from samples. The complete ORF5 genes of 36 PRRSV positive samples was amplified, sequenced and analyzed with other 15 strains available on GenBank. [Result] PRRSV was detected in 118/260 of the clinical samples, with a positive rate was 45.4%. Sequence analysis showed that the 36 isolates of this study belonged to the North American-type PRRSV strains and were closely related to the highly pathogenic PRRSV （HP-PRRSV） with 94.6%-100% amino acid sequence identities. The sequence analysis combined with the phylogenetic analysis indicated that all these North American-type PRRSV strains in East China were further divided into five subgenotypes, subgenotype Ⅲ showed closer identity with HPPRRSV; almost all subgenotypes were found to be variable in the primary neutralizing epitope; subgenotypes Ⅲ and IV had more glycosylation sites than others. Although these 36 isolates were collected from different provinces in East China, there were no obvious relations between the distribution of PRRSV and the region. [Conclusion] The PRRSV infection was widespread and HP-PRRSV was the popular strain in East China during 2008-2010. However some different genetic characteristics appeared in the genomes, the genetic evolution was relatively stable. There exists a cross-cutting phenomenon on the genetic relationship of PRRSV isolates obtained from different provinces. Subgenotypes IV and V only appeared in some provinces, but the distribution of PRRSV did not show apparent geographical characteristics.

Genetic Variation and Differentiation of Larix decidua Populations in Swiss Alps

Genetic diversity within and among six subpopulations of Larix decidua Mill. from two altitudinal transects of Swiss Alps was investigated using 6 enzyme systems coding for 8 loci. Globally, the mean proportion of polymorphic loci was 22.9%, the average number of alleles per locus was 1.3, and the mean expected heterozygosity was 0.095. Only 5.8% of the genetic variation resided among populations. The mean genetic distance was 0.006. Several significant differences of gene frequencies were found between different age classes. Positive values of the species mean fixation index observed in this study suggested a considerable deficit of heterozygotes in the populations of L. decidua of Swiss Alps. At one of the sites (Arpette), the highest subpopulation in elevation gave the lowest level of genetic diversity (as evidenced by the lowest proportion of polymorphic loci and the lowest mean expected heterozygosity) and the largest value of genetic distance when compared to other subpopulations. The genetic differences between the highest subpopulation and the other ones suggest that the founder effect may be an important factor influencing genetic differentiation of L. decidua populations at Arpette transect.

Genetic variation and selection of introduced provenances of Siberian Pine(Pinus sibirica) in frigid regions of the Greater Xing'an Range,Northeast China

Siberian Pine （Pinus sibirica） is an ecologically and eco-nomically important species in pristine forests throughout northern Rus-sia. Four provenances of P. sibirica were introduced from Mongolia and Russia to the Greater Xing’an Range （the Daxing’anling）, northeast China in 1993. The aim of this research was to study genetic variation and selection of the introduced four Pinus sibirica provenances. Heights （H）, basal diameters （BD）, survival rates （SR） and crown lengths （CL） of different families were measured as primary outcomes in different growth years. Results of data analyses demonstrated high coefficients of phenotypic variation （PCV） and heritability （H2） for H, BD and CL at 18 years after introduction. PCV and H2 increased with age. Correlations of＆amp;nbsp;growth traits between any two growth years were all significantly positive, but the correlation coefficient was smaller when the growth year interval was larger. Correlations between H and the original environment factors decreased gradually, indicating that with long-term subsistence in the new environment, the influence of the source environment declined. Colligation of multiple traits to estimate provenances showed that Novosibirsk, Tomsk, and Altai Mountains had higher survival rates and biomass, and proved more suitable for introduction and plantation in the Greater Xing’an Range in China.

Genetic variability and divergence studies in pod and seed traits of Pongamia pinnata(L.) Pierre., accessions in Bay Islands

In this study, we assessed the variability in pod, seed traits and oil content of 24 accessions of Pongamia pinnata collected from different parts of the Andaman and Nicobar Islands, India. The experiment was conducted at the Central Agricultural Research Institute, Port Blair during 2010 to 2011. The variability studies for pod and seed traits revealed that, the accession CPT-6 collected from New Wandoor in South Andaman recorded the maximum values for eight traits viz. pod length （75.51 mm）, pod width （34.62 mm）, pod thickness （17.55 mm）, 100 pod weight （770.33 g）, seed width （21.23 mm）, 100 seed weight （377.00 g）, oil percentage （43.92%） and germination percentage （94.7%）. However, the maximum seed length （26.46 mm） was recorded from CPT 2 and the maximum pod-seed ratio was obtained from CPT 13 and CPT 4 （2.50 and 2.44 respectively）. The phenotypic and genotypic coefficients of variations were also close to each other for all traits, but the 100 pod and seed weight exhibited higher phenotypic and genotypic coefficient of variation than the other traits. Estimates of broad sense heritability ranged from 0.30 （for seed length） to 0.95 （pod length） and genetic ad- vance as percent of the mean ranged between 11.66% and 57.40% with seed length giving the lowest value and 100 pod weight giving the high- est value. Both the phenotypic and genotypic correlation between pod length, pod width, pod thickness, 100 pod weight, seed width and 100 seed weight and between pod thickness, 100 pod weight, seed width, 100 seed weight and germination percentage were found to be strong. On the basis of non hierarchical Euclidian cluster analysis, 24 accessions were grouped into six clusters. The maximum numbers of seven accessions were included in cluster VI. The maximum intra cluster distance （10.238）shown by cluster VI and the maximum inter cluster distance （17.021） between V and HI followed by III and II （15.942）. Among the six clus- ters formed the cluster III recorded maximum oil percentage, 100 pod weight, 100 seed ,weight, pod length, pod thickness, pod width, seed width and. germination percentage, while cluster V recorded maximum pod seed ratio and germination percentage. The present findings suggest that the crossing between accessions of cluster V and cluster III will result in a wide spectrum of variability in subsequent generations.

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.

Genetic variation in distant and inbred hybridization progenies from three sympodial bamboo parent species

To achieve germplasm innovation and study genetic variation of important traits of bamboo plants,we used Bambusa multiplex,B.chungii,and Dendrocalamus latiflorus as parent materials for distant and inbred hybridizations.Two hybrid populations and three inbred populations were obtained:two populations consisted of 57 hybrid progenies from B.multiplex 9 B.chungii,26 hybrid progenies from B.multiplex 9 D.latiflorus,and three inbred progenies were from B.multiplex,B.chungii,and D.latiflorus.Traits for growth,morphology,and fiber were examined from the five populations when plants were 3 years old.Two hybrid populations had significant growth advantages in terms of height,diameter at ground level and internodal length.In terms of variability in morphological traits,the two hybrid populations followed the same trend,namely,seven morphological traits showed phenotypes that were intermediate to those of their parents;three morphological traits showed strong maternal effects,and three other morphological traits showed strong paternal effects.Among the five populations,the two hybrid populations had high arithmetic average fiber length,lengthweighted average fiber length and mass-weighted average fiber length,moreover,extensive variations of these three traits were observed within these two hybrid populations.The establishment of distant hybrid populations from these three bamboo species increased the genetic diversity more than in the other species examined.This work provides excellent materials for breeding new varieties and lays the foundation for understanding the genetics of important traits by analyzing related functional genes.

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.

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.

Geographic variation and genetic performance of Picea koraiensis in growth and wood characteristics

Eight provenances of 19-year-old Picea koraiensis Nakai from the provenancetrials of Maoershan (45°20′N, 127°30′E), Liang-shui (47°10′N, 128°53′E) and Jiagedaqi(50°24′N, 124°07′E) in Northeast China were investigated to analyze the genetic variation ingrowth characteristics (tree height and diameter) and wood characteristics (tracheid length,tracheid diameter, tracheid wall thickness, annual ring width as well as wood density). Greatvariation in height growth and breast height diameter growth was observed among the provenances, andalong with the increase of tree age, these provenances presented different geographic adaptability.The growth characteristics of Picea koraiensis stand at age of 10 in Maoershan and Liangshuiprovenance trials had a positive correlation with longitude, and with increase of tree age to 15 and19, the tree growth of the provenances displayed a significant positive correlation with latitudeas well as altitude. For wood characteristics, great variation was also found among the provenances.There exists a close relation between growth characteristics and wood properties of the provenance.The height and breast height diameter growth of the provenance had a positive correlation withtracheid diameter and annual ring width, and a negative correlation with tracheid wall thickness andwood density. Genetic performance of the provenance in all above characteristics was alsoinvestigated in order to provide more useful information for comprehensive selection of this speciesfor pulpwood and plywood production.

Microsatellite analysis of variation among wild, domesticated, and genetically improved populations of blunt snout bream （Megalobrama amblycephala）

In the present study, the genetic diversity of one selected strain （Pujiang No. 1）, two domesticated populations （GA and HX） and four wild populations （LZ, YN, SS and JL） of blunt snout bream （Megalobrama amblycephala） was analyzed using 17 microsatellite markers. The results showed that an average of 4.88-7.65 number of alleles （A）; an average of 3.20-5.33 effective alleles （Ne）; average observed beterozygosity （Ho） of 0.6985-0.9044; average expected beterozygosity （He） of 0.6501--0.7805; and the average polymorphism information content （PIC） at 0.5706-0.7226. Pairwise FST value between populations ranged from 0.0307-0.1451, and Nei＇s standard genetic distance between populations was 0.0938-0.4524. The expected heterozygosities in the domesticated populations （GA and HX） were significantly lower than those found in three wild populations （LZ, SS and JL）, but no difference was detected when compared with the wild YN population. Likewise, no difference was found between the four wild populations or two domesticated populations. The expected heterozygosity in Pujiang No. 1 was higher than the two domesticated populations and lower than the four wild populations. Regarding pairwise Fsr value between populations, permutation test P-values were significant between the GA, HX and PJ populations, but not between the four wild populations. These results showed that the expected beterozygosity in the selected strain of blunt snout bream, after seven generations of selective breeding, was lower than that of wild populations, but this strain retains higher levels of genetic diversity than domesticated populations. The genetic differences and differentiation amongst wild populations, domesticated populations and the genetically improved strain of blunt snout bream will provide important conservation criteria and guide the utilization of germplasm resources.

Development of the A&GBE base editor for efficiently generating abundant genetic variation in rice

We have developed a dual base editor,rA&GBE,by fusing adenine and glycosylase base editors.It can induce up to eight types of mutations in T0-generation rice,including single-base conversion,simultaneous multiple-base conversions,and InDels,using a single guide RNA.A-to-G and C-to-G/T conversions occur simultaneously on the same DNA strand.The rA&GBE system may prove useful for crop improvement and in planta direct evolution.

Phenotypic and genetic variation between two populations of the Chinese yellow pond turtle, Mauremys mutica (Cantor, 1842)

Mauremys mutica(Cantor,1842)is an endangered species in China.Main phenotypic variations inbody color,body weight,body shape,clutch size,egg size,and hatchling size were revealed betweenthe southern and northern populations.Both populations have the phenomenon of'larger male'sexualsize dimorphism(SSD),especially in the southern population.Furthermore,genetic variations betweenthe two populations were analyzed by RAPD band patterns of 30 random individuals in each population.The average genetic distance was 0.299±0.108 among the samples of two populations.The average ge-netic distance between southern and northern populations was 0.305±0.046.Cluster analysis indicatedthat all the individuals from the southern and northern populations were clustered among themselves toform two distinct clades.A total of 20 population-specific RAPD fragments were scored from 16 primers,and could be used as RAPD markers for distinguishing the southern and the northern population.Basedon the nucleotide sequences of two RAPD markers,two pairs of SCAR primers(SC1-S and SC2-S)weredesigned,which could be used as SCAR markers for the southern population.According to the significantphenotypic and genetic variations,we suggested that the northern population and southern populationmight be considered as two separate taxa,the'northern taxon'and the'southern taxon',and the con-servation should be respectively conducted on the two taxa.