Apogamous Species Research Articles

Sexual and Apogamous Species of Woodferns Show Different Protein and Phytohormone Profiles.

The gametophyte of ferns reproduces either by sexual or asexual means. In the latter, apogamy represents a peculiar case of apomixis, in which an embryo is formed from somatic cells. A proteomic and physiological approach was applied to the apogamous fern Dryopteris affinis ssp. affinis and its sexual relative D. oreades. The proteomic analysis compared apogamous vs. female gametophytes, whereas the phytohormone study included, in addition to females, three apogamous stages (filamentous, spatulate, and cordate). The proteomic profiles revealed a total of 879 proteins and, after annotation, different regulation was found in 206 proteins of D. affinis and 166 of its sexual counterpart. The proteins upregulated in D. affinis are mostly associated to protein metabolism (including folding, transport, and proteolysis), ribosome biogenesis, gene expression and translation, while in the sexual counterpart, they account largely for starch and sucrose metabolism, generation of energy and photosynthesis. Likewise, ultra-performance liquid chromatography-tandem spectrometry (UHPLC-MS/MS) was used to assess the levels of indol-3-acetic acid (IAA); the cytokinins: 6-benzylaminopurine (BA), trans-Zeatine (Z), trans-Zeatin riboside (ZR), dyhidrozeatine (DHZ), dyhidrozeatin riboside (DHZR), isopentenyl adenine (iP), isopentenyl adenosine (iPR), abscisic acid (ABA), the gibberellins GA3 and GA4, salicylic acid (SA), and the brassinosteroids: brassinolide (BL) and castasterone (CS). IAA, the cytokinins Z, ZR, iPR, the gibberellin GA4, the brassinosteoids castasterone, and ABA accumulated more in the sexual gametophyte than in the apogamous one. When comparing the three apogamous stages, BA and SA peaked in filamentous, GA3 and BL in spatulate and DHRZ in cordate gametophytes. The results point to the existence of large metabolic differences between apogamous and sexual gametophytes, and invite to consider the fern gametophyte as a good experimental system to deepen our understanding of plant reproduction.

Origin of the Diplaziumhachijoense complex (Athyriaceae).

We analyzed the phylogeny of the Diplaziumhachijoense complex using plastid trnL-F and low-copy nuclear marker AK1 DNA sequences. Based on allele constitution, triploid apogamous species of the D.hachijoense complex appeared to have originated from the hybridization of triploid apogamous species and diploid sexual species by recurrent hybridization events. These results suggested that triploid apogamous ferns can achieve hybridization with diploid sexual species by producing diploid spores with irregular meiosis in sporogenesis. Furthermore, the present study predicted the involvement of several unknown species associated with hybridization. More sampling of Callipteris species from China and adjacent areas is required to determine the relationships among unknown species and the D.hachijoense complex.

The Distribution of Dryopteris caudipinna (Dryopteridaceae), a Sexually Reproducing Counterpart of the Apogamous D. erythrosora, in Japan

The distribution of Dryopteris caudipinna, a sexually reproducing counterpart of the apogamous species D. erythrosora, was investigated by counting the number of spores per sporangium in a large numbe

Reticulate evolution in the apogamous Dryopteris varia complex (Dryopteridaceae, subg. Erythrovariae, sect. Variae) and its related sexual species in Japan.

Apogamous fern species are often difficult to distinguish from related species because of their continuous morphological variations. To clarify the genetic relationships among the members of the Dryopteris varia complex, we analyzed the nucleotide sequences of the plastid gene rbcL and the nuclear gene PgiC. We also analyzed the diploid sexual species D. caudipinna and D. chinensis, which have not been included in the complex, but were recently shown to be closely related to the complex in a molecular phylogenetic study. The PgiC sequences of the diploid sexual species, D. varia, D. saxifraga, D. sp. 'protobissetiana' (undescribed diploid sexual species), D. caudipinna, and D. chinensis, were well differentiated and hence designated A, B, C, D, and E, respectively. Thus, the PgiC constitution of apogamous species in the complex was as follows: D. bissetiana, B + C; D. kobayashii, B + C + E); D. pacifica, A + C, A + B + C, or A + C + D; D. sacrosancta, A + C + E; and D. saxifragivaria, B + C. These results suggest that these apogamous species are formed by hybridizations of species including not only the three diploid sexual species of the D. varia complex (A, B, and C) but also the two diploid sexual species D. caudipinna (D) and D. chinensis (E), which do not belong to the complex.

Polyploidy and Speciation in Pteris (Pteridaceae)

The highest frequency of polyploidy among plants is considered to occur in the Pteridophytes. In this study, we focused on polyploidy displayed by a specific fern taxon, the genus Pteris L. (Pteridaceae), comprising over 250 species. Cytological data from 106 Pteris species were reviewed. The base number of chromosomes in Pteris is 29. Polyploids are frequently found in Pteris, including triploids, tetraploids, pentaploids, hexaploids, and octoploids. In addition, an aneuploid species, P. deltodon Bak., has been recorded. Furthermore, the relationship between polyploidy and reproductive biology is reviewed. Among these 106 Pteris species, 60% exhibit polyploidy: 22% show intraspecific polyploidy and 38% result from polyploid speciation. Apogamous species are common in Pteris. Diploids are the most frequent among Pteris species, and they can be sexual or apogamous. Triploids are apogamous; tetraploids are sexual or apogamous. Most Pteris species have one to two ploidy levels. The diverse ploidy levels suggest that these species have a complex evolutionary history and their taxonomic problems require further clarification.

Sexuality and apogamy in the Cuban Asplenium auritum–monodon complex (Aspleniaceae)

Asplenium auritum Sw. is a sexual fern that produces 64 spores per sporangium, while A. monodon Liebm. is an apogamous species that produces 32 spores. The hybrid between them, A. × lellingerianum Sanchez & Regalado, also shows an apogamous life cycle, with mainly abortive spores. The scope of this work was to study the sexual and apogamous behavior in these taxa. We studied spore germination and gametophyte development of the three species, a process that followed the Adiantum type. Afterward, we observed morphological apogamous characters in A. monodon and A. × lellingerianum. Apogamous sporophytes arose from apical and basal regions of gametophytes, lacking feet and roots in the first instance, but developing other normal sporophytic structures, such as tracheids, stomata, glandular hairs, and scales. Finally, we studied the gametangia production in all three taxa, finding that the scarce production of antheridia in A. monodon is indicative of the Braithwaite apogamous life cycle scheme, and this scheme has probably been inherited by A. × lellingerianum.

Genetic composition of Swiss and Austrian members of the apogamous Dryopteris affinis complex (Dryopteridaceae, Polypodiopsida) based on ISSR markers

We have investigated genetic variability among 56 individuals of the apogamous Dryopteris affinis complex from 9 populations in Switzerland and Austria using inter-simple sequence repeats. Our sample included 6 diploids, 48 triploids, and 1 tetraploid and 1 pentaploid plant each. We found genetic differences between and within the different ploidy levels. All diploids genetically differed from each other. In contrast, among the triploid plants we only found seven different genotypes of which one was rather common. The tetraploid and pentaploid individuals were nested among the diploids and triploids. No hypotheses have yet been proposed to explain the origin of genetic variations such as those documented here. We hope that this study stimulates new ideas about the position and the genetic background of this taxonomically difficult species group, in particular, and of apogamous species complexes in ferns in general.

RESEARCHES CONCERNING THE IN VITRO DIFFERENTIATION OF THE FERN PHEGOPTERIS CONNECTILIS (MICHX.) WATT

Phegopteris connectilis is an apogamous species, endangered in certain regions. The ex situ conservation, through the in vitro production of the gametophyte, as well as the embryos and the plants, followed by their cryo-stocking, is necessary for ensuring the survival of the endangered species, while at pace with international methodology. The differentiation of the gametophyte is characteristic of the leptosporangiate ferns, passing through the following stages: prothallic filament, prothallic blade, cordate prothallus. The uni- or pluri-serial branchings formed on the gametophytes constitute the initial differentiation stage of a new prothallus. One-cell trichomes are differentiated on the gametophyte, which produce wax, protective against de-hydration. The in vitro culture has evinced the fast life cycle of this species, as the apogamous embryo is formed in the course of only seven weeks after culture inception. The first protophylles are formed out of the apogamous embryo and the initial stem cell is differentiated between the first two. In very few cases, however, it was noticed, at the base of the first leaf, the differentiation of the first root; the latter is formed at a stage when the young sporophyte already has two to three protophylles, as rhizogenesis is favoured by the addition of AIA and Kin in the medium. The plants thus obtained can be utilized for re-establishing the natural populations in the regions where the species is endangered.

Electrophoretic evidence for homoeologous chromosome pairing in the apogamous fern species Dryopteris nipponensis (Dryopteridaceae).

Segregation of genotypes through homoeologous chromosome pairing in the apogamous species Dryopteris nipponensis was tested by electrophoretic analysis. Of 284 progeny examined (250 gametophytes and 34 sporophytes), from the parental sporophyte with the Pgi-2 genotype abc, five showed different genotypes from that of the parent (three aac, one bbc and one bcc). This is the first evidence for genetic segregation in the progeny of apogamous fern species.

Electrophoretic variation of the apogamousDryopteris varia group (Dryopteridaceae)

A total of 35 electrophoretic variants were detected in four apogamous species of theDryopteris varia group: 14 variants inD. bissetiana triploids, 7 inD. sacrosancta triploids, 6 inD. varia triploids, 3 inD. pacifica triploids, and 5 in apogamous diploids. The variants differed from each other in various combinations of a few alleles which were common in some of the variants, suggesting recurrent origin.Dryopteris insularis var.insularis (2x) and var.chichisimensis (3x), other members of the group, were electrophoretically monomorphic, suggesting single origin. Banding patterns infer that triploids ofD. bissetiana andD. sacrosancta may have originated from hybrids whose parent is the sexualD. saxifraga, whereas this species was not involved in the origin of the other apogamous triploids and the apogamous diploids. The other parent was also discussed and we proposed a hypothesis that diploid offsprings fromD. pacifica triploids hybridized withD. saxifraga giving rise to triploids ofD. bissetiana andD. sacrosancta.

Chromosome Numbers and Apomixis in the Fern Genus Bommeria (Gymnogrammaceae)

Species of the fern genus Bommeria occur from the southwestern United States, throughout much of Mexico and into Guatemala, Honduras, Nicaragua and Costa Rica. Acetocarmine squashes of spore mother cells, root tips, and gametophyte meristems have yielded chromosome counts for the five putative species: n - 30, 2n - 60 in B. hispida (Mett.) Underw., B. subpaleacea Maxon, B. ehrenbergiana (KI.) Fourn., and B. knoblochii Maxon; n - 2n = 90 in B. pedata (Sw.) Fourn. The first four of these species are sexual, producing 64 functional spores per sporangium and requiring the addition of free water to gametophyte cultures for sporophyte initiation. Bommeria pedata produces both well developed sporangia containing 32 functional spores and shrunken sporangia with aborted contents. Although gametophytes of B. pedata produce structurally complete archegonia and functional antheridia, culturing and sectioning data indicate that sporophytes arise apogamously near archegonia whose contents are necrotic. The generally greater geographic distribution of B. pedata relative to its sexual congeners may be taken to indicate the present success of this apogamous species. BOMMERIA IS PRESENTLY RECOGNIZED as a genus of five more or less xerically adapted species which are found from the southwestern United States, throughout much of Mexico and into Central America. The approximate ranges of the several species (figs. 1-5) have been determined from herbarium specimen data. Bommeria hispida (fig. 3) is documented from the southwestern United States (western Texas and southern New Mexico, Arizona, and California, though the last not plotted due to lack of precise locality data for the single known collection), Baja California Sur, and throughout much of northwestern Mexico. Bommeria knoblochii (fig. 4) is known only from the original collections of Knobloch in the mountains of western Chihuahua and through recent re-collections from the same localities by Bye. Bommeria ehrenbergiana (fig. 2) has most commonly been collected in the states of Hidalgo and Puebla but reaches as far north as Nuevo Leon. Bommeria subpaleacea (fig. 5) ranges north to the state of Hidalgo and has been collected as far south as Oaxaca. Bommeria pedata (fig. 1) is known from Baja California Sur and is widespread throughout the mountains of northwestern, central, and southern Mexico and through southeastern Guatemala, with rare collections from Honduras, Nicaragua and Costa Rica.

Natural interspecific hybridization between sexual and apogamous species of the beech fern genus Phegopteris Fée

A clone of beech fern found growing on a mountain near Rougemont in Rouville County of Quebec is shown to be a natural hybrid between two species of Phegopteris that grow together at that location, the circumboreal species P. polypodioides Fée and a species endemic to eastern North America, P. hexagonoptera (Michx.) Fée. Phegopteris polypodioides is shown to be an apogamous triploid (2n = 90), P. hexagonoptera a sexual diploid (2n = 60), and the interspecific hybrid between these two species an apogamous tetraploid (2n = 120). It was concluded that the natural hybrid was produced by the union of a motile gamete, containing 90 chromosomes, from an antheridium on a prothallus of apogamous P. polypodioides with a female gamete, containing 30 chromosomes, on a prothallus of sexual P. hexagonoptera. This is the second report of interspecific hybridization between sexual and apogamous species of ferns. The morphology of both parents and the hybrid supports the conclusion that the apogamous species contributed more genetic material to the hybrid than did the sexual species. It is suggested that this hybrid probably occurs at other locations where the ranges of P. polypodioides and P. hexagonoptera overlap.

Trispara‐aspidin, ein neues Phloroglucid aus dem Farn Dryopteris remota (A. Br.) Hayek

AbstractDryopteris remota (A. Br.) Hayek is regarded as a triploid apogamous species, perhaps a hybrid of ♀ D. assimilis Walker with ♂ diploid D. borreri Newm. The phloroglucides (phloroglucinol derivatives) of its rhizomes were investigated; their nature is compatible with the mentioned hypothesis. Besides several known compounds a new tricyclic phloroglucide C36H44O12, designated trispara‐aspidin was isolated. According to mass spectrum and products of reductive cleavage it has the structure given in formula 14.