Analysis of Hypericum accessions by DNA fingerprinting and flow cytometry

Hypericum perforatum, H. umbellatum, H. maculatum, and H. hircinum accessions originating from botanical gardens across Europe were examined by flow cytometry and molecular markers. 2C DNA content of 17 Hypericum perforatum accessions (Hp) and the H. perforatum cultivar Topaz amounted to between 1.56 pg and 1.62 pg. In four Hp accessions some individual plants were found with a DNA content corresponding to 6Cx (2.34 - 2.39 pg). All plants of accession Hp8 showed a DNA content of 6Cx (2.41 pg). In root tips of Hp plants with an average DNA amount of 1.58 pg, 32 chromosomes were detected, corresponding to 2n = 4x. This is the first ploidy and/or DNA content report for H. umbellatum, H. maculatum and H. hircinum. H. umbellatum and H. maculatum, each contained 0.76 pg DNA and 16 chromosomes were counted. The 2C DNA content of H. hircinum was 1.00 pg with the best metaphase plate revealing 32 chromosomes. Additionally, a combined marker analysis, based on inter-simple sequence repeats (ISSR) and sequence related amplified polymorphism (SRAP), was conducted to gain a better understanding of diversity especially within the accessions of H. perforatum. A total of 27 (11 ISSR and 16 SRAP) primer combinations were screened, showing 699 bands, of which 661 were polymorphic. UPGMA clustering revealed that accessions from the same geographic area tended to be more closely related, while H. maculatum was grouped separately from all H. perforatum accessions. Both methods have shown similar sensitivities in detecting the genetic diversity of the analyzed genotypes. Our results may be useful for Hypericum breeding programs and the development of effective conservation strategies.

Genome Size, Chromosome Number and Morphological Data Reveal Unexpected Infraspecific Variability in Festuca (Poaceae)

Polyploidy has played an important evolutionary role in the genus Festuca (Poaceae), and several ploidy levels (ranging from 2n = 2x = 14 to 2n = 12x = 84) have been detected to date. This study aimed to estimate the genome size and ploidy level of two subspecies belonging to the F. yvesii polyploid complex by flow cytometry and chromosome counting. The phenotypic variation of the cytotypes was also explored, based on herbarium material. The genome size of F. yvesii subsp. lagascae has been estimated for the first time. Nuclear 2C DNA content of F. yvesii subsp. summilusitana ranged from 21.44 to 31.91 pg, while that of F. yvesii subsp. lagascae was from 13.60 to 22.31 pg. We report the highest ploidy level detected for Festuca (2n = 14x = 98) and previously unknown cytotypes. A positive correlation between holoploid genome size and chromosome number counts shown herein was confirmed. The morphometric approach showed a slight trend towards an increase in the size of some organs consistent with the variation in the ploidy level. Differences in characters were usually significant only among the most extreme cytotypes of each subspecies, but, even in this case, the high overlapping ranges prevent their distinction.

Chromosome and Ploidy Analysis of Winter Hardy Hibiscus Species by FISH and Flow Cytometry

Determination of nuclear DNA content, genome sizes, and ploidy level and, information on cytogenetic characteristics are all prerequisite of modern plant breeding. However, cytogenetic study of Hibiscus species is often hampered by the similarity in morphology and by the small size of mitotic chromosomes. The goal of the study was to ascertain the chromosome number, karyomorphology, distribution of 5S and 18S rDNA loci, chromosome length, and centromere positions as well as the ploidy level, genome sizes, 2C-DNA content of winter-hardy Hibiscus: H. syriacus ‘Saejamyung’, H. sinosyriacus ‘Seobong’, H. moscheutos ‘Luna Red’ and, H. paramutabilis. 5S rDNA and 18S rDNA loci were detected by fluorescence in situ hybridization (FISH). According to the FISH results, there are two 5S rDNA loci in H. syriacus, H. sinosyriacus, and H. moscheutos, and four 5S rDNA loci in H. paramutabilis. The range in length of somatic chromosomes in H. syriacus, H. sinosyriacus, H. moscheutos, and H. paramutabilis is 2.66- 7.06, 3.18-7.31, 2.91-5.23, and 4.75-7.60 µm, respectively. The 2C-DNA content of H. syriacus, H. sinosyriacus, and H. moscheutos are very similar, the amount was 4.06, 4.11, and, 2.06 pg, respectively whereas, H. paramutabilis has nearly double and the amount was 4.18 pg. These findings will contribute to the detailed cytogenetic assessment of Hibiscus and thus benefit plant breeding in this genus.

Genome Size Diversity in Rare, Endangered, and Protected Orchids in Poland

Orchidaceae is one of the largest and the most widespread plant families with many species threatened with extinction. However, only about 1.5% of orchids’ genome sizes have been known so far. The aim of this study was to estimate the genome size of 15 species and one infraspecific taxon of endangered and protected orchids growing wild in Poland to assess their variability and develop additional criterion useful in orchid species identification and characterization. Flow cytometric genome size estimation revealed that investigated orchid species possessed intermediate, large, and very large genomes. The smallest 2C DNA content possessed Liparis loeselii (14.15 pg), while the largest Cypripedium calceolus (82.10 pg). It was confirmed that the genome size is characteristic to the subfamily. Additionally, for four species Epipactis albensis, Ophrys insectifera, Orchis mascula, Orchis militaris and one infraspecific taxon, Epipactis purpurata f. chlorophylla the 2C DNA content has been estimated for the first time. Genome size estimation by flow cytometry proved to be a useful auxiliary method for quick orchid species identification and characterization.

Checkpoint Regulation of Nuclear Tos4 Defines S Phase Arrest in Fission Yeast

From yeast to humans, the cell cycle is tightly controlled by regulatory networks that regulate cell proliferation and can be monitored by dynamic visual markers in living cells. We have observed S phase progression by monitoring nuclear accumulation of the FHA-containing DNA binding protein Tos4, which is expressed in the G1/S phase transition. We use Tos4 localization to distinguish three classes of DNA replication mutants: those that arrest with an apparent 1C DNA content and accumulate Tos4 at the restrictive temperature; those that arrest with an apparent 2C DNA content, that do not accumulate Tos4; and those that proceed into mitosis despite a 1C DNA content, again without Tos4 accumulation. Our data indicate that Tos4 localization in these conditions is responsive to checkpoint kinases, with activation of the Cds1 checkpoint kinase promoting Tos4 retention in the nucleus, and activation of the Chk1 damage checkpoint promoting its turnover. Tos4 localization therefore allows us to monitor checkpoint-dependent activation that responds to replication failure in early vs. late S phase.

Checkpoint regulation of nuclear Tos4 defines S phase arrest in fission yeast

ABSTRACTFrom yeast to humans, the cell cycle is tightly controlled by regulatory networks that regulate cell proliferation and can be monitored by dynamic visual markers in living cells. We have observed S phase progression by monitoring nuclear accumulation of the FHA-containing DNA binding protein Tos4, which is expressed in the G1/S phase transition. We use Tos4 localization to distinguish three classes of DNA replication mutants: those that arrest with an apparent 1C DNA content and accumulate Tos4 at the restrictive temperature; those that arrest with an apparent 2C DNA content, that do not accumulate Tos4; and those that proceed into mitosis despite a 1C DNA content, again without Tos4 accumulation. Our data indicate that Tos4 localization in these conditions is responsive to checkpoint kinases, with activation of the Cds1 checkpoint kinase promoting Tos4 retention in the nucleus, and activation of the Chk1 damage checkpoint promoting its turnover. Tos4 localization therefore allows us to monitor checkpoint-dependent activation that responds to replication failure in early versus late S phase.

Analysis of chromosome karyotype and genome size in echiuran Urechis unicinctus Drasche, 1880 (Polychaeta, Urechidae)

Karyotype and genome size are two primary cytogenetic characteristics of species, which are of great significance to the study of cytogenetics, taxonomy, phylogenesis, evolution as well as molecular biology. However, this basic cytogenetic information in echiurans is lacking. Therefore, we analyzed characteristics of karyotype and genome size in the echiuran worm Urechisunicinctus Drasche, 1880. In this study, coelomic cells of U.unicinctus were used for analyzing the genome size by a flow cytometry with chicken erythrocytes as DNA standard, and the 2C DNA content was determined to be 1.85 pg, which was corresponded to the genome size of 904.58 Mbp approximately. Furthermore, trochophores of U.unicinctus were dissociated and cells were utilized for preparing the chromosomes stained with DAPI, and the karyotype was determined as 2n = 30 (10m + 6sm + 6st + 8t), FN=52. Our data provided the basic cytogenetic information of U.unicinctus, which could be utilized in taxonomic study and whole-genome sequencing in future.

DNA content estimation of Fig and Black Mulberry using flow cytometry

In this study, fig and black mulberry DNA contents were estimated using DAPI fluorescence stain in flow cytometry. The 2C DNA contents of the fig and black mulberry were found as 0.82 pg and 8.34 pg, respectively. The calculated 1C value of genome size of fig is 401.8 Mbp and that of black mulberry is 4086.6 Mbp. The ratio of 2C DNA content and 1C genome of the black mulberry was 10.17 times that of the fig although fig is diploid and black mulberry is decosaploid.

Determination of DNA content and relative 2C genome sizes of some promising commercial varieties of sugarcane using flow cytometer

<p>In the present study, 2C DNA content and the genome sizes (in picograms-pg and megabase pairs-Mbp respectively) of 19 promising commercial varieties of sugarcane, the derivatives of man-made interspecific hybrids between cultivated and wild species were analyzed using flow cytometry. In this work, 2C nuclear DNA content was determined. Knowing the 2C nuclear DNA content, the unknown chromosome numbers of the varieties could be predicted. Large differences (65 % variation) in DNA content (2C) of 19 varieties were detected, ranging, from 3.80 pg to 10.96 pg, which corresponds to a genome size ranging from 3724.00 Mbp to 10740.80 Mbp due to the variation of ploidy level and are considered the most complex genomes among crop plants. However, the relationship between chromosome number and genome size was highly significant (P &lt; 0.001). In the present study, internode diameter, Sugar juice content and cane yield/ha are also positively correlated with DNA content. The estimated genome sizes would also yield information critical for sugarcane breeding and genome sequencing programs. </p><p><strong>Keywords</strong><strong>: </strong>Genome size, Sugarcane varieties, Flow cytometry, DNA content.</p>