High Levels Of Phenotypic Diversity Research Articles

Genotypic and phenotypic diversity of Bacillus spp. isolated from steel plant waste.

BackgroundMolecular studies of Bacillus diversity in various environments have been reported. However, there have been few investigations concerning Bacillus in steel plant environments. In this study, genotypic and phenotypic diversity and phylogenetic relationships among 40 bacterial isolates recovered from steel plant waste were investigated using classical and molecular methods.Results16S rDNA partial sequencing assigned all the isolates to the Bacillus genus, with close genetic relatedness to the Bacillus subtilis and Bacillus cereus groups, and to the species Bacillus sphaericus. tDNA-intergenic spacer length polymorphisms and the 16S–23S intergenic transcribed spacer region failed to identify the isolates at the species level. Genomic diversity was investigated by molecular typing with rep (repetitive sequence) based PCR using the primer sets ERIC2 (enterobacterial repetitive intergenic consensus), (GTG)5, and BOXAIR. Genotypic fingerprinting of the isolates reflected high intraspecies and interspecies diversity. Clustering of the isolates using ERIC-PCR fingerprinting was similar to that obtained from the 16S rRNA gene phylogenetic tree, indicating the potential of the former technique as a simple and useful tool for examining relationships among unknown Bacillus spp. Physiological, biochemical and heavy metal susceptibility profiles also indicated considerable phenotypic diversity. Among the heavy metal compounds tested Zn, Pb and Cu were least toxic to the bacterial isolates, whereas Ag inhibited all isolates at 0.001 mM.ConclusionIsolates with identical 16S rRNA gene sequences had different genomic fingerprints and differed considerably in their physiological capabilities, so the high levels of phenotypic diversity found in this study are likely to have ecological relevance.

Development and application of microsatellite markers for genomic analysis of papaya

Papaya has a relatively small genome, displays high levels of phenotypic diversity, and is amenable to transformation, making it attractive as a fruit tree model system. The high level of phenotypic diversity seen among papaya cultivars in the field does not correlate with the low levels of genotypic polymorphism thus far elucidated. The highly mutable nature of microsatellites or simple sequence repeats (SSRs) make them potentially powerful markers for distinguishing deoxyribonucleic acid (DNA) polymorphisms between closely related genotypes. Genomic research for papaya has resulted in a significant quantity of sequence data. We mined 28.1 Mb of bacterial artificial chromosomes end sequences, 5.8 Mb of complementary DNA, and 1.6 Mb of random genomic sequences for SSRs. We generated 938 SSR markers and tested for polymorphism among seven varieties that had been used to produce five mapping populations. The level of polymorphism was highest for Kaek Dum × 2H94 with 210 markers, followed by UH928 × SunUp with 194, AU9 × SunUp with 189, UH918 × SunUp with 177, and Kapoho × SunUp displaying the lowest level with 97. Variation in levels of polymorphism, motif predominance, and motif length between the genomic and genic fractions indicated differential selection pressures acting on the microsatellites in these two fractions. The microsatellites developed in this study will greatly assist in the genetic and physical mapping of the papaya genome as well as enhance breeders’ ability to improve the crop.

Phenotypic polymorphism for superoxide dismutase in grape

Multiple isoforms of superoxide dismutase (SOD) occurred in grape following an electrophoretic analysis of 75 grapevine accessions. Three activity zones were resolved, and were designated as Sod-1, Sod-2 and Sod-3 in order of their anodal electrophoretic mobility. For the banding pattern and staining intensity, no differences were observed in both ploidy level and somatic mutation. From the controlled cross tests among SOD variants, the grape SOD was presumed as a dimeric enzyme. The grapevine accessions examined exhibited a high level of phenotypic diversity which could be separated into 13 groups on the basis of SOD zymogram. A remarkable difference in SOD phenotypes was recognized between the cultivated varieties and the wild species and rootstocks. Furthermore, we discussed the associations between SOD phenotypes and agronomically important features, especially seedlessness and lime-induced chlorosis.