Gametophyte Structure Research Articles

Characterization of pollen development and female reproductive structure of Phalaenopsis amabilis after pollination

Abstract. Udkhiawati I, Solicahatun, Pitoyo A. 2020. Characterization of pollen development and female reproductive structure of Phalaenopsis amabilis after pollination. Cell Biol Dev 4: 17-25. Orchid is a superior commodity in ornamental plants. Enthusiasts of orchids cause the demand for varieties diversity. Orchids often get obstacles in pollination, so it is necessary to characterize the development of post-pollination pollen and female gametophyte structure. Characterization was conducted through in vitro and in vivo methods. This research aims to determine the development of pollen and female gametophyte structure of Phalaenopsis amabilis (L.) Blume after pollination and detect the potential of in vitro pollen germination. This research was explorative. It involves methods were in vitro pollen germination and preparation of anatomy of pollen and ovule of the 1st DAP (Day After Pollination), 2nd DAP, 3rd DAP, 4th DAP, 7th DAP, 20th DAP, 30th DAP, 50th DAP, and 60th DAP. The observations included in vitro culture of pollen cultured in Brewbaker and Kwack (mBK) media using a phase-contrast microscope and observation of anatomical development of post-pollination pollen tube and ovule using a fluorescence microscope. The observed data consisted of in vivo female gametophytes and pollen development in vitro and in vivo methods. The data were analyzed descriptively. From observation of post-pollination pollen, it was known that the pollen tube started to germinate on the 2nd -3rd DAP. At the 7th DAP, all pollens had germinated and formed the pollen tube, and then the pollen tubes continued to grow closer to the ovule. Primordial ovule began to form on the 7th DAP, then continued to develop a seed on 60th DAP, and then an embryo pouch formed. The in vitro pollen germination did not show any change in pollen after 30th DAC (Day After Cultivating).

The moss calyptra: A maternal structure influencing offspring development

The calyptra is a small, maternal gametophyte structure that covers the apex of the offspring sporophyte and is critical for the transition from seta formation to capsule differentiation in many moss taxa. It has been hypothesized to function by (1) providing a mechanical constraint that coordinates the development of the presumptive capsule, (2) secreting hormones that influence sporangium differentiation, (3) physically protecting the undifferentiated capsule region, (4) preventing water loss from the sporophyte apex, and/or (5) lowering the rate of sporophyte transpiration. This review explores the experiments that have tested these hypotheses and the evidence that has been found to support or refute them from scientific literature dating back to the late 1700's. Across mosses, calyptrae come in a wide array of shapes and sizes, which may correlate with aspects of morphology, habitat, and function. The overarching objective of this paper is to renew discussion about and research into this small, but important moss organ.

Phylogenetic inference and peristome evolution in haplolepideous mosses, focusing on Pseudoditrichaceae and Ditrichaceaes. l.

Pseudoditrichum mirabile, the only species of Pseudoditrichaceae, has been known for a long time from a single collection from the Canadian Arctic. Its systematic position remained enigmatic due to similarity in gametophyte structure with Ditrichaceae, a family that has simple peristomes, whereas the peristome in Pseudoditrichum is double. Due to this difference, Pseudoditrichum was classified in either Funariales or Bryales. A recent discovery of this species in the Anabar Plateau in northern Siberia has allowed its phylogenetic position to be tested based on plastid rps4 and rbcL and mitochondrial nad5 sequences. The results of this research reject the earlier hypotheses. Instead, the molecular analysis resolves Pseudoditrichum in a clade with Chrysoblastella chilensis (formerly Ditrichaceae) in the haplolepideous lineage. The peristome of Pseudoditrichum is of a previously unknown type with a fully developed exostome and hyaline endostome elements opposite the exostome teeth, based not on the 4:2:4 peristomial formula, but on 4:2:3. Double peristomes of the same type, albeit rather strongly reduced, occur in Catoscopium, Chrysoblastella, Distichium and Ditrichum flexicaule. The polyphyly of Ditrichaceae is confirmed by molecular phylogenetic analysis, and Ditrichum flexicaule and D. gracile are segregated into the new genus Flexitrichum and family Flexitrichaceae. An independent status of the recently resurrected family Distichiaceae is supported, and segregation of Chrysoblastella and Saelania into new monospecific families is proposed.

The developmental basis of an evolutionary diversification of female gametophyte structure in Piper and Piperaceae.

Fritillaria-type female gametophyte development is a complex, yet homoplasious developmental pattern that is interesting from both evolutionary and developmental perspectives. Piper (Piperaceae) was chosen for this study of Fritillaria-type female gametophyte development because Piperales represent a 'hotspot' of female gametophyte developmental evolution and have been the subject of several recent molecular phylogenetic analyses. This wealth of phylogenetic and descriptive data make Piper an excellent candidate for inferring the evolutionary developmental basis for the origin of Fritillaria-type female gametophytes. Developing ovules of Piper peltatum were taken from greenhouse collections, embedded in glycol methacrylate, and serially sectioned. Light microscopy and laser scanning confocal microscopy were combined to produce three-dimensional computer reconstructions of developing female gametophytes. The ploidies of the developing embryos and endosperms were calculated using microspectrofluorometry. The data describe female gametophyte development in Piper with highly detailed three-dimensional models, and document two previously unknown arrangements of megaspore nuclei during early development. Also collected were microspectrofluorometric data that indicate that Fritillaria-type female gametophyte development in Piper results in pentaploid endosperm. The three-dimensional models resolve previous ambiguities in developmental interpretations of Fritillaria-type female gametophytes in Piper. The newly discovered arrangements of megaspore nuclei that are described allow for the construction of explicit hypotheses of female gametophyte developmental evolution within Piperaceae, and more broadly throughout Piperales. These detailed hypotheses indicate that the common ancestor of Piperaceae minus Verhuellia had a Drusa-type female gametophyte, and that evolutionary transitions to derived tetrasporic female gametophyte ontogenies in Piperaceae, including Fritillaria-type female gametophyte development, are the consequence of key nuclear migration and patterning events at the end of megasporogenesis.

Female gametophyte development inAristolochia labiataWilld. (Aristolochiaceae)

Piperales are an extremely diverse angiosperm lineage in terms of female gametophyte structure and, as such, an excellent candidate for comparative investigations of developmental evolution. In Piperales, Aristolochiaceae are sister to clades in which several divergent patterns of female gametophyte development are prevalent. Outgroup comparisons and explicit analyses of character evolution demonstrate that Polygonum-type female gametophyte development and structure in Aristolochiaceae appears to represent the plesiomorphic condition from which the divergent ontogenies of Piperales evolved. Here, we present detailed analyses of female gametophyte development in Aristolochia labiata that combine light and confocal microscopy with three-dimensional computer reconstruction. Our reconstructions demonstrate that, at the two-nucleate stage of development, separation of nuclei to opposite poles of the female gametophyte does not appear to be dependent on vacuolar expansion as generally hypothesized. We also found a decrease in antipodal volume following formation of the secondary nucleus. Our data provide a baseline for future efforts to describe developmental modifications responsible for evolutionary transitions in female gametophyte ontogeny throughout Piperales. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 19‐29.

The effects of methionine and cobalt ions on sex expression and development of Anemia phyllitidis gametophytes

One of the prime precursor for ethylene synthesis — L-methionine and the inhibitor of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) — Co2+-were tested for their effects on sex expression and development of Anemia phyllitidis fern gametophytes. Five concentrations of both chemicals (0, 10, 25, 50, 100 µM) were analysed with reference to antheridia and archegonia formation, number and size of cells as well as thalli length using the three-zone model of gametophyte structure. Both substances, however at different concentrations, enhanced the number of GA3-induced antheridia and similarly stimulated the cell number and inhibited thalli length. Both of them at 100 µM concentrations without GA3 induced meristematic area formation while methionine also induced archegonia in the apical parts of gametophytes. These findings correspond with the previous observations concerning the important role of ethylene synthesis precursor (ACC) in controlling gibberellic acid-induced male sex expression in ferns and broaden the knowledge about the mechanisms of fern gametophyte development.

Megagametogenesis in Arabidopsis wild type and the Gf mutant

The female gametophyte is an essential structure for angiosperm reproduction that mediates a host of reproductive functions and, following fertilization, gives rise to most of the seed. Here, we describe a rapid method to analyze Arabidopsis female gametophyte structure using confocal laser scanning microscopy (CLSM). We present a comprehensive description of megagametogenesis in wild-type Arabidopsis. Based on our observations, we divided Arabidopsis megagametogenesis into eight morphologically distinct stages. We show that synergid cell degeneration is triggered by pollination, that dramatic nuclear migrations take place during the four-nucleate stage, and that megagametogenesis within a pistil is fairly synchronous. Finally, we present a phenotypic analysis of the previously reported Gf mutant (Redei 1965) and show that it affects an early step of megagametogenesis.

The developmental anatomy ofMetaxya rostrata (Filicales: Metaxyaceae)

The systematically problematic fern Metaxya rostrata, commonly regarded as an ally of the cyatheoid and dicksonioid tree ferns, is investigated, and features of its organography, shoot vascular anatomy and development, soral initiation and early development, and gametophyte structure are described. The rhizome is creeping, dorsiventral, with an unusual four‐seriate phyllotaxis. Typical protoxylem is lacking from the intemodes of the solenostele, but are present in the leaf trace and end blindly proximally. Tangential cells are found in the phloem of the stem. The early maturing “protoxylem” of the stem is scattered, and, apart from some identifiable protoxylem strands, is not clearly associated with the young leaves. Sori are initiated as groups of large cells on the abaxial side of developing leaflets, distant from the marginal meristem initials, and in close association with a lateral vein. Two sori may arise by the subdivision of a single large patch of cells. Soral maturation is of the simple type. Gametophytes are cordate to ribbonlike, with moderately primitive gametangia. Morphologically and systematically, Metaxya appears isolated. It shares few significant derived conditions with the tree ferns, and a separate family Metaxyaceae seems well justified.

The Developmental Anatomy of Metaxya rostrata (Filicales: Metaxyaceae)

The systematically problematic fern Metaxya rostrata, commonly regarded as an ally of the cyatheoid and dicksonioid tree ferns, is investigated, and features of its organography, shoot vascular anatomy and development, soral initiation and early development, and gametophyte structure are described. The rhizome is creeping, dorsiventral, with an unusual four-seriate phyllotaxis. Typical protoxylem is lacking from the intemodes of the solenostele, but are present in the leaf trace and end blindly proximally. Tangential cells are found in the phloem of the stem. The early maturing “protoxylem” of the stem is scattered, and, apart from some identifiable protoxylem strands, is not clearly associated with the young leaves. Sori are initiated as groups of large cells on the abaxial side of developing leaflets, distant from the marginal meristem initials, and in close association with a lateral vein. Two sori may arise by the subdivision of a single large patch of cells. Soral maturation is of the simple type. Gametophytes are cordate to ribbonlike, with moderately primitive gametangia. Morphologically and systematically, Metaxya appears isolated. It shares few significant derived conditions with the tree ferns, and a separate family Metaxyaceae seems well justified.

Germinación de esporas y gametofitos de "Polystichum montevidense" (Spreng.) Rosenst. ("Dryopteridaceae")

A description is made of characteristics of the germination of spores, gametophytic development and adult gametophyte structure of Polystichum montevidense (Spreng.) Rosenst. obtained by sterile culture. It was found that sporangia produce 32 monolete spores with crested perispore. The germination of Vittaria-type spores occurs three days after sowing. Gametophyte development is of the Aspidium type. The laminar gametophytes have only one type of glandular trichomes, with secretion of trichomes has a lipid nature, distributed on the edge of the lamina and a few on the surface. It is reported for the first time that adult gametophyte cells have oil droplets. Sexual expression is manifested in gametophytes of more than 100 days old, with only female gametophytes. All this is illustrated with pictures recorded with light microscopes and a scanning electron microscope.