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PubMed2026

[Genetic diversity analysis of Forsythia suspensa germplasm resources in Shanxi based on phenotypic traits and SNP molecular markers].

This study aimed to clarify the degree of fruit phenotypic variation and the characteristics of genetic diversity, population structure, and genetic differentiation of Forsythia suspensa resources in Shanxi, providing an important basis for germplasm conservation and breeding of superior varieties. A total of 46 F. suspensa fruits were collected, and 12 agronomic traits were measured and analyzed. The population genetic structure and genetic diversity of F. suspensa germplasm were evaluated using simplified genome sequencing technology. For the five quality traits of the 46 fruits, the Shannon-Wiener index ranged from 0.631 to 1.074, and the Simpson index ranged from 0.379 to 0.560. The seven quantitative traits exhibited abundant genetic variation, with coefficients of variation ranging from 9.764%(fruit shape index) to 45.494%(forsythin content). Principal component analysis reduced the 12 phenotypic traits to four factors, with a cumulative variance contribution of 74.547%. Sequencing data showed mean Q20 and Q30 values of 98.13% and 94.33%, respectively, with an average GC content of 35.95%. After filtering, a total of 12 347 327 high-quality single nucleotide polymorphism(SNP) loci were obtained. Based on these high-quality SNPs, principal component analysis, population structure analysis, and phylogenetic tree construction were carried out. The 46 germplasm resources were divided into four groups; however, grouping showed little relationship with geographic origin, and intermixing occurred among regions. Mantel test revealed a significant but weak positive correlation between phenotypic and genetic distances(r=0.159, P=0.001). At the molecular level, the four groups exhibited moderate genetic diversity overall, and the genetic differentiation index among populations ranged from 0.027 to 0.084, indicating low to moderate differentiation. The rich genetic diversity of the main phenotypic traits provides a solid material basis for screening superior germplasm and genetic breeding of F. suspensa.

Forsythia↗
PubMed1998

Synthesis and diversity analysis of lead discovery piperazine-2-carboxamide libraries.

A Lead Discovery Library of piperazine-2-carboxamide derivatives was produced for general screening. This paper discloses two novel solid phase synthetic routes used to produce 15,000 single compounds via the Irori directed sorting technique. Computational methods such as reagent clustering and library profiling were used to maximize reagent diversity and optimize pharmacokinetic parameters. The results of a four center pharmacophore analysis revealed the added diversity gained by using two independent synthetic routes.

Combinatorial Chemistry Techniques↗
PubMed2006

Frequency of HIV type 1 dual infection and HIV diversity: analysis of low- and high-risk populations in Mbeya Region, Tanzania.

HIV-1 diversity, frequency of recombinants, and dual infection were determined in two populations with different HIV risk behavior. A high-risk cohort of 600 female bar workers and a normal-risk population of 1,108 antenatal clinic attendees and blood donors were recruited. Behavioral data were assessed and blood for HIV- 1 diagnosis and genotyping was sampled. HIV-1 subtypes were defined through the multiregion hybridization assay (MHA(acd)). HIV-1 prevalence differed significantly among the two populations. The prevalence was 67.8% in the population of bar workers and 17% in the normal-risk population (antenatal care attendees and blood donors). Within the normal-risk population the HIV-1 prevalence was lowest in the group of volunteer blood donors. The frequency of HIV-1 infection in women was 1.7 times higher than in men. The overall subtype distribution was A (8.5%), C (40.8%), D (3.8%), AC (25.4%), AD (5.4%), CD (8.8%), and ACD (7.3%). In the high-risk population there was a higher percentage of HIV-1 recombinant strains (54% vs. 40%, p < 0.05) and a higher frequency of dual infections (19% vs. 9%, p < 0.02) compared to the normal-risk population. High-risk populations may play an important role in the evolution of HIV, as they can provide an opportunity for the virus to coinfect, recombine, and adapt to the host-specific genetic background.

Adolescent↗
PubMed2004

Diversity analysis of commensal porcine Escherichia coli - associations between genotypes and habitat in the porcine gastrointestinal tract.

Diversity studies of enteric Escherichia coli have relied almost entirely on faecal isolations on the assumption that they are representative of flora found throughout the gastrointestinal tract. The authors have addressed this belief by analysing isolates obtained from the duodenum, ileum, colon and faeces of pigs. E. coli isolates were obtained from eight pigs and characterized using multi-locus enzyme electrophoresis and PCR-based screening for a range of factors thought to be associated with intestinal and extra-intestinal disease. There are four main genetic groups of commensal E. coli (A, B1, B2, D). Group A strains represented 76 % of the isolates from the duodenum, ileum and colon compared to 58 % of the strains isolated from faeces. A nested molecular analysis of variance based on the allozyme and virulence factor screening results showed that differences among individual pigs accounted for 6 % of the observed genetic diversity, whilst 27 % of the genetic variation could be explained by clonal composition differences among gut regions. Finally, the absence of virulence genes in these commensals indicates that they may be suitable as a probiotic consortium, particularly if they also display increased adherence to enterocytes and antagonistic activity against pathogenic strains of E. coli.

Animals↗
PubMed2004

Nested PCR for detection and genotyping of Ehrlichia ruminantium: use in genetic diversity analysis.

Ehrlichia ruminantium, the agent of cowdriosis transmitted by Amblyomma ticks, presents an extensive genetic and antigenic diversity of key importance for vaccine formulation. Two means of nested polymerase chain reaction (PCR) targeting were developed to conduct molecular epidemiology studies in the Caribbean and Africa. The first used a conserved DNA fragment for detection of the pathogen in animals and vectors, and the second relied on the polymorphic map1 gene for genotyping. As compared to a PCR, the nested PCR showed a 2-Log10 improvement of sensitivity and allowed amplification from ticks, blood, brain, and lungs from infected animals, providing a more accurate picture of the tick infection rate. In Guadeloupe, this rate reached 36% (N = 212) instead of 1.7% (N = 224), as previously estimated. Genetic typing was done by restriction fragment length polymorphism or sequencing of map1 amplification products. Molecular epidemiology studies conducted in field sites selected for vaccination trials with inactivated vaccine, revealed the circulation of genetically divergent strains in limited geographical areas. It is known, then, that genetic clustering based on map1 has no predictive value regarding the protective value of a given strain against a new strain. However, tracing the strains by this technique revealed the extent of E. ruminantium diversity that one can expect in a given region, and the method allows differentiation between an inadequate immune response and the challenge by a breakthrough strain on animals dying despite vaccination. Up to now, genetic typing does not avoid cross-protection studies, which were conducted in parallel, although on a more limited scale. The importance of pathogen diversity studies for optimization of vaccine design is discussed as well as the research for new polymorphic genes. These genes may allow better predictions on cross-protection, given the recent completion of the sequence of the full genome of two E. ruminantium strains.

Animals↗
PubMed2006

Double-barreled wet colostomy is a safe option for simultaneous urinary and fecal diversion. Analysis of 56 procedures from a single institution.

BACKGROUND AND OBJECTIVES: Wide pelvic tumors need urinary and fecal diversion. We set out to assess the efficacy of the double-barreled wet colostomy (DBWC) in patients undergoing simultaneous double diversion. MATERIAL AND METHODS: We reviewed 56 consecutive patients submitted to surgery, divided into two groups: (1) total pelvic exenteration plus DBWC (n = 26); (2) DBWC without simultaneous pelvic resection (n = 30). Pelvic tumor recurrences accounted for most patients (n = 53), whereas the remaining three patients suffered from actinic pelvic complications. RESULTS: Surgical morbidity and mortality rates were 53.8% (14/26) and 11.5% (3/26) in Group 1, and 43.5% (13/30) and 3.3% (1/30) in Group 2, respectively. Only 2 patients out of 51 (3.9%) developed late postoperative urinary tract infection. Regression of the hydronephrosis was observed in 28 out of 33 assessable patients. Median survival in Groups 1 and 2 was 8.36 and 4.14 months, respectively. In the subgroup of patients submitted to curative surgery (n = 24), actuarial cancer-specific survival rate in 2 years was 58.78%. CONCLUSION: DBWC is a safe and efficient alternative for simultaneous urinary and fecal diversion, with low morbidity and mortality rates, improvement of renal insufficiency, and low risk of postoperative urinary tract infection.

Adult↗
PubMed2006

Amplification and diversity analysis of ketosynthase domains of putative polyketide synthase genes in Aspergillus ochraceus and Aspergillus carbonarius producers of ochratoxin A.

The diversity of polyketide synthase (PKS) genes in Aspergillus ochraceus NRRL 3174 and Aspergillus carbonarius 2Mu134 has been investigated using different primer pairs previously developed for the ketosynthase (KS) domain of fungal PKSs. Nine different KS domain sequences in A. ochraceus NRRL 3174 as well as five different KS domain sequences in A. carbonarius 2Mu134 have been identified. The identified KS fragments were distributed in five different clusters on the phylogenetic tree, indicating that they most probably represent PKSs responsible for different functions.

Amino Acid Sequence↗
PubMed2006

Genetic diversity analysis using lowly polymorphic dominant markers: the example of AFLP in pigs.

DNA markers are commonly used for large-scale evaluation of genetic diversity in farm animals, as a component of the management of animal genetic resources. AFLP markers are useful for such studies as they can be generated relatively simply; however, challenges in analysis arise from their dominant scoring and the low level of polymorphism of some markers. This paper describes the results obtained with a set of AFLP markers in a study of 59 pig breeds. AFLP fingerprints were generated using four primer combinations (PC), yielding a total of 148 marker loci, and average harmonic mean of breed sample size was 37.3. The average proportion of monomorphic populations was 63% (range across loci: 3%-98%). The moment-based method of Hill and Weir (2004, Mol Ecol 13:895-908) was applied to estimate gene frequencies, gene diversity (F(ST)), and Reynolds genetic distances. A highly significant average F(ST) of 0.11 was estimated, together with highly significant PC effects on gene diversity. The variance of F(ST) across loci also significantly exceeded the variance expected under the hypothesis of AFLP neutrality, strongly suggesting the sensitivity of AFLP to selection or other forces. Moment estimates were compared to estimates derived from the square root estimation of gene frequency, as currently applied for dominant markers, and the biases incurred in the latter method were evaluated. The paper discusses the hypotheses underlying the moment estimations and various issues relating to the biallelic, dominant, and lowly polymorphic nature of this set of AFLP markers and to their use as compared to microsatellites for measuring genetic diversity.

Animals↗
PubMed1999

Diversity analysis of 14 156 molecules tested by the National Cancer Institute for anti-HIV activity using the quantitative structure-activity relational expert system MCASE.

Using the MCASE program, a procedure to analyze the diversity of the large amount of available HIV-1 antiviral data was proposed. A subset of 1 819 chemicals was logically selected from the original 14 156 chemicals tested by NCI. This subset of chemicals was shown to contain most of the structural and the functional information of the original database. A full analysis of the 1 819 chemicals by the MCASE program produced a correlation between chemical structures and HIV antiviral activity. In our model, 74 fragments were identified as being responsible for all the chemical's HIV antiviral activity. These fragments may be related to different inhibiting mechanisms, some known and some probably still unknown. The expert system resulting from this analysis can be used to predict the activity of new chemicals and to design new agents that can target multiple enzymes. This was shown to be the case by using the model to predict the activity of 10 diverse chemicals whose activities were not known at the time of model development. Of these, 8 were predicted in agreement with experimental observations. As far as we can tell, this is probably the first project ever to attempt to create a quantitative model of activity for such a massive database of diverse chemicals.

Anti-HIV Agents↗
PubMed2004

Mitochondrial diversity analysis of Glossina palpalis gambiensis from Mali and Senegal.

West African riverine tsetse populations of Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) were investigated for gene flow, inferred from mitochondrial diversity in samples of 69 flies from Senegal and 303 flies from three river drainages in Mali. Four polymorphic mitochondrial loci were scored. Mean haplotype diversities were 0.30 in Mali, 0 in Senegal and 0.18 over both Mali and Senegal. These diversities estimate the probabilities that two randomly chosen tsetse have different haplotypes. Substantial rates of gene flow were detected among flies sampled along tributaries belonging to the river basins of the Senegal, Niger, and Bani in Mali. There was virtually no gene flow between tsetse in Senegal and Mali. No seasonal effects on gene flow were detected. The implications of these preliminary findings for the implementation of area-wide integrated pest management (AW-IPM) programmes against riverine tsetse in West Africa are discussed.

Animals↗
PubMed2005

[Complications of Bricker ileal conduit urinary diversion: analysis of a series of 246 patients].

OBJECTIVE: The objective of this retrospective study was to evaluate the mortality and early and late morbidities of Bricker ileal conduit urinary diversion. PATIENTS AND METHODS: Between January 1990 and December 2002, 246 Bricker ileal conduit urinary diversion was performed in our centre in 164 males (67%) and 82 females (33%) with a mean age of 64 years (range: 9 to 90 years). Bricker diversion was performed in 73.6% of cases for underlying tumour (prostate, bladder, cervical, colon cancer), and in 26.4% of cases for benign disease (neurogenic bladder radiation bladder bladder exstrophy, incrusting cystitis). Cystectomy was associated with Bricker diversion in 62.2% of cases. The mean follow-up was 24 months (range: 1 to 151 months). The following parameters were studied: mortality and early and late medical or surgical, urological and gastrointestinal complications. RESULTS: The postoperative mortality was 6.9% (17 deaths, 16 in patients in whom Bricker diversion was performed for cancer). The early morbidity was marked by gastrointestinal complications (ileus, fistula, evisceration) in 46 cases (1.7%), 25 of which required re-operation. A medical complication was observed in 41 patients (16.7% of the series), responsible for 60% of the postoperative mortality (10 of the 17 deaths). A urinary fistula was observed in 7 patients (2.8%). The late morbidity consisted of parietal complications (incisional hernia, peristomal hernia, stricture of the stoma) in 18.3% of cases. Urological complications consisted of acute pyelonephritis (11%), ureteroileal stricture (4.9%) and urinary stones (4.9%). CONCLUSION: Bricker ileal conduit urinary diversion is associated with considerable mortality, especially in cancer patients. Early complications are essentially gastrointestinal, while late complications tend to be parietal or urological.

Adolescent↗
PubMed2005

[16S rDNA diversity analysis of 30 Streptomycetes isolates displaying significant cytotoxic activity against B16 cell from near-shore sediments of Hainan Island].

A total of 354 isolates of actinomycetes, of which 76 were detected cytotoxic activity was isolated from near-shore marine samples collected at Wenchang mangrove, DanZhou harbor and YanPu harbor. Four isolation methods were employed, which are SDS pretreatment, phenol pretreatment, heating pretreatment and potassium dichromate selection culture, and media such as'Yeast extract-Malt extract (YE), Glucose-Asprine (GA), Starch-Casin (SC), Starch-KNO3 (Gause) were used. It was showed that heating pretreatment and potassium dichromate selection culture were more considerable methods for extensive isolation of actinomycetes. Medium YE and Gause showed best results in both the total number of actinomycetes and the number of active isolates against tumor cell B16. The genotypic diversity of 30 strains of Streptomycetes possessing strong cytotoxic activity against B16 cell (ID50 > or =200) was analyzed by 16S ARDRA, which resulted in 17 RFLP types, and indicated relatively rich genotypic diversity among these Streptomycetes. 16S rDNA sequence analysis of three strains, 050642, 060386 and 060524 (ID50 > or = 1200) further confirmed that they all belong to Streptomyces genus and strain 050642 was suggested a novel Streptomyces. Spp with the highest similarity of 95% to Streptomyces cattleya.

Animals↗
PubMed1993

Comparative diversity analysis of RFLPs and isozymes within and among populations of Hordeum vulgare ssp. spontaneum.

DNA restriction fragment length polymorphisms (RFLPs) and isozyme variation were surveyed in 268 accessions of a wild barley (Hordeum vulgare ssp. spontaneum) sampled from diverse ecogeographical areas in Israel and Iran. A total of 24 markers was used: 7 well characterized isozyme loci and 15 DNA probes which detected 17 putative loci and included three classes of DNA sequences (single copy, low copy and repetitive) representing all 7 barley chromosomes. Survey results indicated that both RFLPs and isozymes are highly polymorphic both within and among populations of this wild barley. The number of alleles per locus and average level of diversity do not differ between isozymes and RFLPs. However, the relative amounts of within vs. between population components vary greatly between these two sets of molecular markers. Isozymes demonstrated a larger amount of within population diversity, whereas RFLPs resolved a higher proportion of between population differentiation. Furthermore, RFLPs detected more heterozygosity than did isozymes. Both classes of markers resolved large numbers of multilocus combinations, the majority of which were represented by only one individual in the total sample. Up to 30% of the loci differ among individuals within populations, and about 50% of the loci differ among plants in different populations. While many important aspects of population diversity as determined by RFLPs are significantly correlated with those of isozymes, such correlation values are generally low, indicating that only a small proportion of the genetic variation detected by one class of markers can be predicted by the other.

Alleles↗
PubMed2004

Genetic diversity analysis in valencia peanut (Arachis hypogaea L.) using microsatellite markers.

Cultivated peanut or groundnut (Arachis hypogaea L) is an important source of oil and protein. Considerable variation has been recorded for morphological, physiological and agronomic traits, whereas few molecular variations have been recorded for this crop. The identification and understanding of molecular genetic diversity in cultivated peanut types will help in effective genetic conservation along with efficient breeding programs in this crop. The New Mexico breeding program has embarked upon a program of improvement of Valencia peanut (belonging to the sub species fastigiata), because efforts to improve the yield potential are lacking due to lack of identified divergent exotic types. For the first time, this study has shown molecular diversity using microsatellite markers in the cultivated Valencia peanut (sub spp. fastigiata) from around the globe. In this investigation, 48 cultivated Valencia peanut genotypes have been selected and analyzed using 18 fluorescently labeled SSR (f-SSR) primer pairs. These primer pairs amplified 120 polymorphic loci among the genotypes screened and amplified from 3 to 19 alleles with an average of 6.9 allele per primer pair. The f-SSR marker data was further analyzed using cluster algorithms and principal component analysis. The results indicated that (1) considerable genetic variations were discovered among the analyzed genotypes; (2) The f-SSR based clustering could identify the putative pedigree types of the present Valencia types of diverse origins, and (3) The f-SSR in general is sufficient to obtain estimates of genetic divergence for the material in study. The results are being utilized in our breeding program for parental selection and linkage map construction.

Arachis↗
PubMed2006

Genetic diversity analysis of Tibetan wild barley using SSR markers.

One hundred and six accessions of wild barley collected from Tibet, China, including 50 entries of the two-rowed wild barley Hordeum vulgare ssp. spontaneum (HS), 29 entries of the six-rowed wild barley Hordeum vulgare ssp. agriocrithon (HA), and 27 entries of the six-rowed wild barley Hordeum vulgare ssp. agriocrithon var. lagunculiforme (HL), were analyzed using 30 SSR markers selected from the seven barley linkage groups for studying genetic diversity and evolutionary relationship of the three subspecies of Tibetan wild barley to cultivated barley in China. Over the 30 genetic loci that were studied, 229 alleles were identified among the 106 accessions, of which 70 were common alleles. H. vulgare ssp. spontaneum possesses about thrice more private alleles (2.83 alleles/locus) than HS (0.93 alleles/locus), whereas almost no private alleles were detected in HL. The genetic diversity among-subspecies is much higher than that within-subspecies. Generally, the genetic diversity among the three subspecies is of the order HS > HL > HA. Phylogenetic analysis of the 106 accessions showed that all the accessions of HS and HA was clustered in their own groups, whereas the 27 accessions of HL were separated into two groups (14 entries with group HS and the rest with group HA). This indicated that HL was an intermediate form between HS and HA. Based on this study and previous works, we suggested that Chinese cultivated barley might evolve from HS via HL to HA.

Alleles↗
PubMed2026

Diversity analysis of indoor and outdoor fungal bioaerosols in UK households: a prospective, observational, longitudinal study.

BACKGROUND: Long-term exposure to indoor fungal bioaerosols is a recognised risk factor for respiratory illness, particularly in damp and poorly ventilated housing. However, the diversity and seasonal variability of these fungal communities are poorly understood. As part of the West London Healthy Home and Environment Study (WellHome), this study aimed to characterise the composition, diversity, and temporal dynamics of indoor fungal bioaerosols in urban UK homes, as compared with outdoor air, to inform future exposure baselines and policy development. METHODS: In this prospective, community-based observational study, 118 households were recruited across West London, UK, via community networks and partner organisations, prioritising families with children aged 5-17 years with asthma or allergies, from diverse socioeconomic backgrounds. Sampling occurred between Oct 3, 2022, and June 14, 2024. Participant data were collected via questionnaires completed by household members, capturing demographics, building characteristics, and respiratory health. Passive-air samplers were used in living rooms for 28 days during two seasonal campaigns, with concurrent outdoor sampling at four fixed community sites. Fungal bioaerosols were identified by ITS2 amplicon sequencing and quantified using broad-range quantitative PCR targeting the 18S rRNA gene. Diversity indexes and temporal dynamics were analysed using ecological statistics and generalised additive models. FINDINGS: 118 households were enrolled, comprising 504 residents (263 women, 237 men, and four not reported). Among 504 participants who self-identified, the largest groups comprised individuals identifying as Black African (n=47), Somali (n=46), White British (n=42), and African (n=38), with additional representation from mixed race ethnic backgrounds (n=29), Black British (n=27), White (n=22), and Black Caribbean (n=18), alongside several other ethnicities each represented at lower frequencies. Of 118 households, 104 completed both seasonal campaigns and 14 completed one, yielding 262 air samples (222 indoor and 40 outdoor). DNA was successfully recovered from all samples, identifying 2027 fungal genera. Indoor environments showed significantly higher richness (mean 646 vs 495 amplicon sequence variants; p<0&#xb7;0001) and Shannon diversity (4&#xb7;21 vs 3&#xb7;53; p<0&#xb7;0001) than outdoors. Community composition differed markedly (permutational multivariate ANOVA p<0&#xb7;0001), with Penicillium, Aspergillus, and Wallemia enriched indoors. Indoor fungal communities presented stronger seasonal cycling (R2=0&#xb7;203) than outdoor communities (R2=0&#xb7;012). Fungal burden across all homes had a median 11&#x2009;043 genomic equivalence (GE); IQR 4598-20&#x2009;579 GE. The highest levels were observed in homes with visible mould; one household showed elevated Aspergillus exposure linked to repeated asthma hospitalisations in a sensitised resident. INTERPRETATION: Indoor fungal bioaerosols are more diverse and dynamic than outdoor communities in urban UK homes. These findings establish foundational exposure data and highlight the need for incorporating fungal bioaerosol monitoring into public health policy to mitigate mould-related health risks. FUNDING: UK Research and Innovation (UKRI) Strategic Priorities Fund (SPF) Clean Air Programme.

Humans↗
PubMed2003

Evaluation of maize microsatellite markers for genetic diversity analysis and fingerprinting in sugarcane.

The use of maize microsatellite markers as a potential cost-effective method for molecular analysis of sugarcane was evaluated. Of the 34 primer pairs obtained from maize genomic libraries, 14 showed repeatable amplifications in Saccharum species clones, commercial hybrids, and the related genera Erianthus, accounting for 41.17% cross transferability. Complex banding patterns were encountered in sugarcane with the number of amplified fragments ranging from 7 to 14 with an average of 10 per primer, indicating the high polyploidy and heterozygosity existing in sugarcane. Phenetic analysis of the SSR polymorphisms produced by nine primers could clearly differentiate the different species of Saccharum and Erianthus and revealed the relationships that existed between them. Genetic similarity co-efficient indicated low diversity existing among the S. officinarum clones (82%) and a relatively higher level of diversity in the S. spontaneum clones (69.7%). Higher level of divergence of Erianthus from Saccharum was also clearly estabilished. Five primers produced genus- and species-specific fragments for Erianthus, S. spontaneum, S. officinarum, and S. barberi. The polymorphic primers, when tested on a panel of 30 commercial sugarcane cultivars, revealed a broad range (32.4-83.3%) of pair-wise similarity values, indicating their ability to detect high levels of polymorphism. A combination of two primers could differentiate all the varieties, further emphasizing their potential in fingerprinting and varietal identification.

Cluster Analysis↗
PubMed2004

[Genetic diversity analysis of maize recurrent selection populations by SSR marker].

Two cycles of mass (MS) and half-sib (HS) recurrent selection and one cycle of marker-assisted selection (MAS) for yield were carried out in two synthetic maize populations DC0 and XFC0, respectively. The genetic diversity of five maize (Zea mays L.) populations, including basic population DC0 and its developed populations HSC2, MSC2, and basic population XFC0 and its developed populations XFC1, were evaluated by 49 SSR primers, which are averagely distributed on 10 maize chromosomes. On the 49 SSR loci, a total of 185 alleles had been detected in these populations. At each locus, 1 to 7 alleles could be detected, with an average of 3.8. The proportion of polymorphic sites differed in the five maize populations, which were 90.3%, 85.9%, 84.9%, 85.9%, 80.5% for DC0, HSC2, MSC2, XFC0 and XFC1, respectively. Genotypes can be showed by the difference of the alleles detected on the 49 SSR loci. There were totally 430, 392, 377, 399 and 395 genotypes for DC0, HSC2, MSC2, XFC0 and XFC1, respectively. The mean gene heterozygosity calculated from the 185 alleles were 0.660, 0.644, 0.645, 0.662 and 0.655 for DC0, HSC2, MSC2, XFC0 and XFC1, respectively. All these results mean that after selection the ranges of variance of the populations decreased slightly. And the mean genetic distance calculated from the 185 alleles were 0.4695, 0.4696, 0.4698, 0.4836 and 0.4902 for DC0, HSC2, MSC2, XFC0 and XFC1, respectively. There was nearly no difference after selection in both the basic populations. Analyses on the distribution of genetic distance showed that most of the genetic distances in the developed populations were smaller than in the basic populations. But the ranges of the genetic distance were wider after selection in both populations. This result indicated that heterogeneity between some of the individuals in the developed populations increased after several times of recombination and exchange. All these indexes demonstrated that the genetic diversity of selection populations was similar to their primary populations, and genetic variation was maintained during recurrent selection.

Genetic Variation↗