Cytological relationships between three diploid species of the fern genus Ceratopteris

1977 ◽  
Vol 55 (12) ◽  
pp. 1660-1667 ◽  
Author(s):  
Leslie G. Hickok
Keyword(s):  
Diploid Species ◽  
Genetic Differences ◽  
Individual Chromosome ◽  
Structural Rearrangements ◽  
Species Relationships ◽  
Genomic Level ◽  
Cytological Data ◽  
Homosporous Fern ◽  
Homosporous Ferns ◽  
Chromosomal Homologies

The cytological and reproductive characteristics of synthesized hybrids involving three diploid species of the homosporous fern genus Ceratopteris Brongn. have been examined. Cytological data indicate that the three species have major chromosomal homologies but differ with respect to a few structural rearrangements involving translocations and inversions. All of the hybrids were semi-sterile but F2 generations were obtained in which moderate to full fertility was evident. No relationship was evident between the degrees of morphological similarities between the species and the degrees of cytological and genetic differences expressed in the hybrids. These factors have confused species relationships among the diploid members of the genus. The behavior of the diploid hybrids is unique among the homosporous ferns in that cytological differences between the species involve individual chromosome differences rather than differences or similarities at the genomic level.

Cytogenetic analysis of interspecific hybrids and amphiploids between two diploid crested wheatgrasses, Agropyron mongolicum and A. cristatum

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1079-1084 ◽  
Author(s):  
Catherine Hsiao ◽  
Kay H. Asay ◽  
Douglas R. Dewey
Keyword(s):  
Chromosome Pairing ◽  
Morphological Variation ◽  
Reciprocal Translocation ◽  
Interspecific Hybrids ◽  
Diploid Species ◽  
Structural Rearrangements ◽  
Short Chromosome ◽  
Cytological Data ◽  
Broad Array ◽  
Pairing Behavior

Agropyron mongolicum Keng, the narrow linear-spiked diploid species (2n = 14), was hybridized with the broad pectinate-spiked diploid (2n = 14), A. cristatum (L.) Gaertner. The F1 hybrids were all diploids and morphologically intermediate to their parents. Chromosome pairing at metaphase I in the hybrids averaged 1.40 I, 5.59 II, 0.35 III, and 0.09 IV per cell, demonstrating that the two parental genomes are very similar. The F1 hybrids were partially fertile. The F2 progeny showed a broad array of variations in spike morphology and chromosome pairing behavior. Cytological data of the F1 hybrids and the F2 progeny revealed that these two diploid species contain the same basic P genome but differ by structural rearrangements of some chromosomes. The patterns of multivalent associations were the result of a heterozygous reciprocal translocation between a long and a very short chromosome segment. The colchicine-induced C0 amphiploids were fully fertile with regular chromosome pairing behavior. These two diploid species are the likely source of morphological variation in the tetraploid crested wheatgrasses.Key words: Agropyron, cytogenetics, chromosome pairing, interspecific hybrids.

scholarly journals The C-Fern (Ceratopteris richardii) genome: insights into plant genome evolution with the first partial homosporous fern genome assembly

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
D. Blaine Marchant ◽  
Emily B. Sessa ◽  
Paul G. Wolf ◽  
Kweon Heo ◽  
W. Brad Barbazuk ◽  
...  
Keyword(s):  
Genome Evolution ◽  
Green Plant ◽  
Land Plant ◽  
Plant Genome ◽  
Flowering Plant ◽  
Ceratopteris Richardii ◽  
Repeat Elements ◽  
Homosporous Fern ◽  
Homosporous Ferns ◽  
Large Genomes

AbstractFerns are notorious for possessing large genomes and numerous chromosomes. Despite decades of speculation, the processes underlying the expansive genomes of ferns are unclear, largely due to the absence of a sequenced homosporous fern genome. The lack of this crucial resource has not only hindered investigations of evolutionary processes responsible for the unusual genome characteristics of homosporous ferns, but also impeded synthesis of genome evolution across land plants. Here, we used the model fern species Ceratopteris richardii to address the processes (e.g., polyploidy, spread of repeat elements) by which the large genomes and high chromosome numbers typical of homosporous ferns may have evolved and have been maintained. We directly compared repeat compositions in species spanning the green plant tree of life and a diversity of genome sizes, as well as both short- and long-read-based assemblies of Ceratopteris. We found evidence consistent with a single ancient polyploidy event in the evolutionary history of Ceratopteris based on both genomic and cytogenetic data, and on repeat proportions similar to those found in large flowering plant genomes. This study provides a major stepping-stone in the understanding of land plant evolutionary genomics by providing the first homosporous fern reference genome, as well as insights into the processes underlying the formation of these massive genomes.

Triploidy and its evolutionary significance in Cystopteris protrusa

1985 ◽  
Vol 63 (10) ◽  
pp. 1855-1863 ◽  
Author(s):  
Christopher H. Haufler ◽  
Michael D. Windham ◽  
Donald M. Britton ◽  
Scott J. Robinson
Keyword(s):  
Environmental Stress ◽  
Diploid Species ◽  
Intermediate Stage ◽  
Evolutionary Significance ◽  
Polyploid Formation ◽  
Homosporous Ferns ◽  
Diploid Gametes ◽  
Diploid Populations

The most widely recognized mode of polyploid formation in homosporous ferns is allopolyploidy. There are taxa, however, that appear to have arisen through autopolyploidy. Several widely separated collections of the normally diploid species Cystopteris protrusa were found to be triploid. Plants in these collections were morphologically similar to typical, diploid C. protrusa, exhibited a significant number of trivalents during meiosis, and corresponded allozymically to heterozygotes from diploid populations. These plants probably arose through outcrossing between normal, haploid gametes and unreduced, diploid gametes. It is hypothesized that this mechanism of autopolyploid formation is stimulated by environmental stress and may be an intermediate stage in the formation of sexually reproductive tetraploids.

ANALYSIS OF SPECIES RELATIONSHIPS IN AVENAE BY THIN-LAYER CHROMATOGRAPHY AND DISC ELECTROPHORESIS

1972 ◽  
Vol 14 (2) ◽  
pp. 305-316 ◽  
Author(s):  
H. C. Dass
Keyword(s):  
Thin Layer ◽  
Diploid Species ◽  
Disc Electrophoresis ◽  
Tetraploid Species ◽  
Species Relationships ◽  
D Genome ◽  
Genome Donor ◽  
A Genome ◽  
Layer Chromatography ◽  
Esterase Patterns

Thin-layer chromatographic studies on flavonoids, and disc electrophoretic studies on proteins and esterase isoenzymes were conducted with Avena to determine species relationships and genome homologies. Distinctness of Avena ventricosa and A. pilosa was observed in comparison to other diploid species. Closeness of the diploid species of the A. strigosa group (including hirtula and wiestii) was evident from the similarity of their protein and esterase spectra. The tetraploid species, A. barbata and A. abyssinica, were found to be very close to A. hirtula and A. strigosa, respectively, by TLC studies. Proteins and esterases also showed that the tetraploid species are very close to the A. strigosa group of diploid species. The contribution of a genome by the A. strigosa group to the tetraploids and hexaploids was confirmed. The hexaploids showed different protein and esterase patterns. The involvement of A. ventricosa as the C genome donor to the hexaploids was shown by the protein and esterase spectra. A few extra protein bands observed may have been from the D genome.

scholarly journals Species Relationships inDichanthiumV. The Diploid Species

Caryologia ◽  
1964 ◽  
Vol 17 (1) ◽  
pp. 153-160 ◽  
Author(s):  
J. M. J. De Wet ◽  
A. P. Singh
Keyword(s):  
Diploid Species ◽  
Species Relationships

Restriction fragment length polymorphism based phylogenetic analysis of Avena L.

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1279-1284 ◽  
Author(s):  
Rita Alicchio ◽  
Lina Aranci ◽  
Lucia Conte
Keyword(s):  
Fragment Length Polymorphism ◽  
Phylogenetic Analyses ◽  
Diploid Species ◽  
The Other ◽  
Molecular Approach ◽  
Polyploid Species ◽  
Species Relationships ◽  
Biochemical Traits ◽  
A Genome ◽  
Restriction Fragment Length

We report a molecular approach to the study of the phylogenetic relationships of Avena diploid and polyploid species based on RFLP detected with three cDNA probes of nuclear genes belonging to multigenic families (low pI α-amylase, avenin, and globulin). All the probes were highly informative in the detection of polymorphism between oat species. Associations between species were determined from cluster (UPGMA) analysis based on distance values calculated from RFLP data separately for each of the two levels of ploidy. Results were in general agreement with morphology based phylogenetic analyses, confirming the large differentiation among A and C genomes in the evolution of diploid species and the genetic homogeneity among A. brevis, A. strigosa, and A. nuda and the recently discovered A. atlantica. A certain divergence was observed between two endemic species (A. canariensis and A. damascena) and the other diploid species with the A genome. The analysis of tetraploid species relationships confirms the differentiation of the barbata complex (A. wiestii, A. barbata, A. abyssinica, and A. vaviloviana) from the maroccana–murphyi–agadiriana group, which, despite some similarities in morphological and biochemical traits, seems to have accumulated deep genetic differences along its evolutionary pathway.Key words: Avena genomes, genetic distance, ploidy, RFLP, multigenic families.

Multiple ribosomal RNA gene loci in the genome of the homosporous fern Ceratopteris richardii

1999 ◽  
Vol 77 (8) ◽  
pp. 1199-1202 ◽  
Author(s):  
J Mitchell McGrath ◽  
Leslie G Hickok
Keyword(s):  
In Situ Hybridization ◽  
Gene Silencing ◽  
Ribosomal Rna ◽  
Genome Structure ◽  
Plant Genome ◽  
Ceratopteris Richardii ◽  
Rdna Loci ◽  
Homosporous Fern ◽  
Homosporous Ferns

The genomes of homosporous ferns are largely uncharacterized, but they appear to differ from gymnosperms and angiosperms in key aspects, such as high chromosome numbers at the diploid level, and thus provide a unique perspective on plant genome structure and evolution. Using the model homosporous fern Ceratopteris richardii, loci encoding ribosomal RNA sequences (rDNA genes) were detected using fluorescent in situ hybridization. At least two major rDNA loci were visible in all cases, and six or more weakly hybridizing signals were observed in most cytological preparations. These results are consistent with models of homosporous fern evolution via cycles of polyploidy followed by gene silencing. They are also consistent with other models of fern genome evolution. With the exception of the weakly hybridizing signals, these data are similar to analogous reports of one or two major rDNA loci in diploid angiosperms. These results suggest that the gross morphology of rDNA loci are similar between diploid homosporous ferns and angiosperms, but that important clues to rDNA gene and chromosome evolution in homosporous ferns may reside in the analysis of their minor rDNA sequences.Key words: rDNA, in situ hybridization, homosporous ferns, evolution, gene silencing, polyploidy.

scholarly journals Cytotaxonomic studies in African Asclepiadaceae

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 795-798 ◽  
Author(s):  
F. Albers
Keyword(s):  
Diploid Species ◽  
Morphological Characters ◽  
Chromosome Morphology ◽  
Basic Chromosome Number ◽  
Individual Identification ◽  
Flower Structure ◽  
Cytological Data ◽  
South Arabia ◽  
The Family ◽  
Morphological Differences

The family Asclepiadaceae of about 290 genera is a homogeneous complex with complicated flower-structure. Little cytological data are available on the approximately 3 000 species in the family. The best studied subtribe is the Ceropegiinae (sensu Schumann, 1895) including the Stapelieae (as presently recognized) with its dominantly succulent members. Exactly half of the species are known karyologically. The basic chromosome number in the family is x = 11 and in most of the genera polyploid taxa are also to be found. The small size of the chromosomes makes individual identification very difficult and they form a graded series with very slight morphological differences. C-banding permits identification of heterochromatic regions; they all take up near centromeric positions. Therefore, studies aimed at an analysis of relationships with the aid of chromosome morphology on a lower taxonomic level, will hardly be possible. In so far as morphological characters of the inflorescence are concerned, diploid species of the genus Caralluma seem to form a species centre in South Arabia/East Africa.

Species relationships between antifungal chitinase and nuclear rDNA (internal transcribed spacer) sequences in the genus Hordeum

Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 339-347 ◽  
Author(s):  
Alfredo De Bustos ◽  
Yolanda Loarce ◽  
Nicolás Jouve
Keyword(s):  
Concerted Evolution ◽  
Internal Transcribed Spacer ◽  
Sequence Data ◽  
Diploid Species ◽  
Species Relationships ◽  
Nuclear Rdna ◽  
Hordeum Murinum ◽  
Internal Transcribed Spacer Sequences ◽  
Antifungal Chitinase

The sequences of the chitinase gene (Chi-26) and the internal transcribed spacer of 18S – 5.8S – 26S rDNA (ITS1) were determined to analyze the phylogenetic relationships among species representing the four basic genomes of the genus Hordeum. Grouping analysis based on data for Chi-26 gene sequences placed Hordeum secalinum (H genome) near the Hordeum murinum complex (Xu genome), and Hordeum bulbosum distant from the other species that carried the I genome. ITS sequence data showed the expected grouping based on the genome classification of the species studied. Different sequences of ITS were detected even in the genomes of the diploid species. The results are interpreted in terms of defective or unfinished concerted evolution processes in each taxon.Key words: ITS, Hordeum, phylogeny, chitinase, concerted evolution.

Genetic differences between humans and chimps and among humans.

1979 ◽  
Vol 34 (2) ◽  
pp. 188-190 ◽  
Author(s):  
Robert Plomin ◽  
A. R. Kuse
Keyword(s):  
Genetic Differences
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