• Journal of Environmental Science International
• /
• v.20 no.2
• /
• pp.155-161
• /
• 2011

In application and discussion of population structure and phenotypic divergence in plant community, the classic Lotka-Volterra models of competition and spatial model are conceived as a mechanism that is composed by multiple interacting processes. Both the Lotka-Volterra and spatial simulation formulae predict that species diversity increases with genotypic richness (GR). The two formulae are also in agreement that species diversity generally decreases within increasing niche breadth (NB) and increases with increasing potential genotypic range (PGR). Across the entire parameter space in the Lotka-Volterra model and most of the parameter space in the spatial simulations, variance in community composition decreased with increasing genotypic richness. This was, in large part, a consequence of selecting genotypes randomly from a set pool.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2006.05a
• /
• pp.127-128
• /
• 2006

• Journal of Korean Society of Forest Science
• /
• v.96 no.6
• /
• pp.667-675
• /
• 2007

The genetic diversity and the spatial structure in two populations of Abelia tyaihyoni in Yeongwol region were studied by employing I-SSR markers. In spite of the limited distribution and small population sizes of Abelia tyaihyoni, the amount of genetic diversity estimated at the individual level was comparable to other shrub species (S.I.=0.336, h=0.217). Genetic diversity at the genet level was very similar to that at individual level. (S.l.=0.339, h=0.219). About 18.7 percent of total variation was allocated between two populations, which was slightly higher or similar level as compared with other shrub species. Genotypic diversity estimated by the ratio of the number of genets ($N_G$) over the total number of individuals (N) and a modified Simpson's index ($D_G$) were also higher than those of other shrubs. The maximum diameter of a genet did not exceed 5.5 m. The high level of gene and genotypic diversity, and the relatively limited maximum diameter of a genet suggested that the clonal propagation is not the most dominant factor in determining the population structure of Abelia tyaihyoni. Spatial autocorrelation analysis revealed significant spatial genetic structure within 12 m and 18 m distances in two populations A and B, respectively. Autocorrelations among individuals at the both individual and genet levels in each population didn't show any considerable differences. As a sampling strategy for ex-situ conservation of populations showing continuous distribution, a minimum distance of 18 m between individuals was recommended. For the populations with many segments, it was considered very crucial to sample materials from as many segments as possible.

• The Plant Pathology Journal
• /
• v.27 no.2
• /
• pp.128-137
• /
• 2011

Fifty two Macrophomina phaseolina isolates were recovered from 24 host plant species through the 14 Iranian provinces. All isolates were confirmed to species using species-specific primers. The colony characteristics of each isolate were recorded, including chlorate phenotype, relative growth rate at $30^{\circ}C$ and $37^{\circ}C$, average size of microsclerotia, and time to microsclerotia formation. The feathery colony phenotype was the most common (63.7%) on the chlorate selective medium and represented the chlorate sensitive phenotype of the Iranian Macrophomina phaseolina population. Meantime, inter simple sequence repeats (ISSR) Markers were used to assess the genetic diversity of the fungus. Unweighted pair-group method using arithmetic means (UPGMA) clustering of data showed that isolates did not clearly differentiate to the specific group according to the host or geographical origins, however, usually the isolates from the same host or the same geographic origin tend to group nearly. Our results did not show a correlation between the genetic diversity based on the ISSR and phenotypic characteristics. Similar to the M. phaseolina populations in the other countries, the Iranian isolates were highly diverse based on the phenotypic and the genotypic characteristics investigated and needs more studies using neutral molecular tools to get a deeper insight into this complex species.

• Journal of Veterinary Clinics
• /
• v.25 no.3
• /
• pp.139-145
• /
• 2008

To investigate the genotypic diversity of the porcine reproductive and respiratory syndrome viruses (PRRSV) in Korea, we examined 92 clinical samples from three provinces by RT-PCR and a nested PCR, and the complete open-reading frame 7 (ORF 7) sequences of 15 samples selected from 72 PCR-positive specimens were analyzed. When we compared nucleotide (amino acid) sequences of 80 isolates from Korea and overseas countries, the sequences of 7 samples belonged to North American (NA)-genotype, and those of 8 samples, to European (EU)-genotype. The nucleotide (amino acid) identities between two genotypes were 63.7% (59.8%) to 65.1% (63.1%). When compared with NA prototype VR-2332, the 7 strains of NA-genotype shared 89.8% (93.6%) to 91.2% (96.0%) identity of nucleotide (amino acid) sequence. The 8 strains of EU-type shared 93.6% (92.3%) to 94.3% (93.8%) identity of nucleotide (amino acid) sequence as compared to EU prototype Lelystad. In phylogenetic tree analysis by neighbor-joining method, all of the 8 EU-type strains were clustered into group 4 distinct from ED-prototype Lelystad (group 1). In NA-genotype, 24 domestic isolates reported previously and the 7 strains of NA-type determined in this study were clustered into group 1, while US prototype VR 2332 was classified into different group (group 2). These results suggest that emergence of EU-genotype and the dual-infection of NA- and EU-genotypes may be prevalent in the pig farms in Korea. The high degree of genetic diversity of field PRRSVs should be taken into consideration for control and preventive measures.

• Korean Journal of Veterinary Service
• /
• v.46 no.4
• /
• pp.315-324
• /
• 2023

This study was carried out to investigate the genotypic diversity of PCV2 and co-infection of PCV3 in the hilar lymph nodes of 700 randomly-selected slaughter pigs. Fourteen samples per each farm were obtained from 50 farms between February and August in 2022. Of the 50 farms, 44 farms that had been positive for PCV2 by RT-PCR were genotyped. As a result of PCV2 genotyping, positive rate of PCV2 DNA was 62.3% (436/700). Among the PCV2 DNA-positive samples, positive rate of a single PCV2 genotype was 79.1% (345/436), while multiple PCV2 genotypes were only detected in 20.9% (91/436). Of the 436 single infection cases, PCV2d genotype was most prevalent. Positive rates of PCV2 and PCV3 were 53.6% and 26.0% at the sample level, 5.1% and 8.0% at the farm level, respectively. And the co-positive rate of two viruses was 8.7% (61/700) at the sample level, 62.0% (31/50) at the farm level. These results demonstrate that PCV2 prevalence in slaughter pigs is very high and co-infection between different PCV2 genotypes and between PCV2 and PCV3 is relatively common. Therefore, genetic diversity and co-infection between other porcine circoviruses should be consistently monitored in the future.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.3
• /
• pp.672-677
• /
• 2005

The standard reference collection of strains for E. coli, the ECOR collection, was analyzed by a genome-based typing method. Seventy-one ECOR strains were subjected to repetitive extragenic palindromic PCR genome fingerprinting with BOX primers (BOX-PCR). Using a similarity value of 0.8 or more after cluster analysis of BOX-PCR fingerprinting patterns to define the same genotypes, we identified 28 genotypes in the ECOR collection. Shannon's entropy-based diversity index was 3.07, and the incident-based coverage estimator indicated potentially 420 genotypes among E. coli populations. Chi-square test of goodness-of-fit showed statistically significant association between the genotypes defined by BOX-PCR fingerprinting and the groups previously defined by multi-locus enzyme electrophoresis. This study suggests that the diversification of E. coli strains in natural populations is actively ongoing, and rep-PCR fingerprinting is a convenient and reliable method to type E. coli strains for the purposes ranging from ecology to quarantine.ine.

• Korean Journal of Environmental Biology
• /
• v.18 no.1
• /
• pp.53-61
• /
• 2000

In order to characterize the genetic diversity of bacterial community in groundwater, samples were collected from used for drinking water and polluted with heavy metal wastewater in Seoul city and natural cave of Kangwondo. The DNA was amplified with 165 rDNA-based primers by use of the PCR, and then analysed ARDRA (amplified ribosomal DNA restriction analysis). Restriction endonuclease analysis patterns of amplified 165 rDNA in drinking water and wastewater relatively showed high genetic diversity in situ and drinking groundwater. The number of DNA fragments varied with in situ and drinking water. This method of ARDRA of bacterial communities in groundwater could be used for a quick assessment of genotypic changes between different locations reflecting different environmental conditions and the diversity reflected pollution of groundwater (natural cave water>drinking water>waste water, as in order of grade). [Genetic diversity, Groundwater, 165 rDNA, PCR, ARDRA].

• The Plant Pathology Journal
• /
• v.22 no.1
• /
• pp.28-35
• /
• 2006

Virulence and genetic diversity were studied using 21 isolates of Sclerospora graminicola, the pearl millet downy mildew pathogen collected from major pearl millet growing areas of India. Variability for virulence was determined by inoculating a set of 10 differential hosts with the S. graminicola isolates in a greenhouse. The isolates varied for latent period (6.4 to 11 days), disease incidence (0 to $98\%$), virulence index (0 to 18.7) and oospore-production potential (1 to 4). Among the 21 isolates, Sg 139 (Rajasthan) was the most virulent and Sg 110 (Tamil Nadu) the least virulent. Based on virulence index (disease incidence$\time$slatent $period^{-1}$), the 21 isolates were classified into eight virulence groups. Genetic diversity among isolates was studied using AFLP markers. Based on similarity index of banding pattern, the 21 isolates were clustered into eight genotypic groups. The AFLP groupings, however, did not match with that of the virulence groupings, and these two were found independent. The isolate Sg 139 that remained distinct in both pathogenic and genetic groupings indicated its highly virulent nature. Implications of these results in downy mildew resistance breeding are discussed.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.1
• /
• pp.13-24
• /
• 2012

The genetic diversity of plant growth-promoting rhizobacterial (PGPR) fluorescent pseudomonads associated with the sugarcane (Saccharum officinarum L.) rhizosphere was analyzed. Selected isolates were screened for plant growthpromoting properties including production of indole acetic acid, phosphate solubilization, denitrification ability, and production of antifungal metabolites. Furthermore, 16S rDNA sequence analysis was performed to identify and differentiate these isolates. Based on 16S rDNA sequence similarity, the isolates were designated as Pseudomonas plecoglossicida, P. fluorescens, P. libaniensis, and P. aeruginosa. Differentiation of isolates belonging to the same group was achieved through different genomic DNA fingerprinting techniques, including randomly amplified polymorphic DNA (RAPD), amplified ribosomal DNA restriction analysis (ARDRA), repetitive extragenic palindromic (REP), enterobacterial repetitive intergenic consensus (ERIC), and bacterial repetitive BOX elements (BOX) analyses. The genetic diversity observed among the isolates and rep-PCR-generated fingerprinting patterns revealed that PGPR fluorescent pseudomonads are associated with the rhizosphere of sugarcane and that P. plecoglossicida is a dominant species. The knowledge obtained herein regarding the genetic and functional diversity of fluorescent pseudomonads associated with the sugarcane rhizosphere is useful for understanding their ecological role and potential utilization in sustainable agriculture.