Ultrastructure and development of sporoderm in Andreaeobryum macrosporum Steere &amp; B.M. Murray (Andreaeobryopsida)

Polevova, Svetlana; Spirina, Ulyana N.; Ignatov, Michael S.

doi:10.1016/j.revpalbo.2022.104621

Cited by 2 publications

(1 citation statement)

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“…Aspects of spore development in mosses have been reported in diverse taxa, including Sphagnum ( Brown et al, 1982 ), Andreaea ( Brown and Lemmon, 1984 ), Andreaeobryum ( Polevova et al, 2022 ), and Takakia ( Renzaglia et al, 1997 ), the sister taxa to peristomate mosses. Among bryopsid mosses, sporogenesis has been examined in scattered taxa, including Trematodon ( Brown and Lemmon, 1981 ), Ditrichum ( Brown and Lemmon, 1980 ), Timmiella ( Gambardella et al, 1993 ; Gambardella et al, 1994 ), Archidium ( Brown and Lemmon, 1985 ), and Amblystegium ( Brown and Lemmon, 1982 ).…”

Section: Introductionmentioning

confidence: 99%

Sporogenesis in Physcomitrium patens: Intergenerational collaboration and the development of the spore wall and aperture

Renzaglia

Ashton

Suh

2023

Front. Cell Dev. Biol.

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Although the evolution of spores was critical to the diversification of plants on land, sporogenesis is incompletely characterized for model plants such as Physcomitrium patens. In this study, the complete process of P. patens sporogenesis is detailed from capsule expansion to mature spore formation, with emphasis on the construction of the complex spore wall and proximal aperture. Both diploid (sporophytic) and haploid (spores) cells contribute to the development and maturation of spores. During capsule expansion, the diploid cells of the capsule, including spore mother cells (SMCs), inner capsule wall layer (spore sac), and columella, contribute a locular fibrillar matrix that contains the machinery and nutrients for spore ontogeny. Nascent spores are enclosed in a second matrix that is surrounded by a thin SMC wall and suspended in the locular material. As they expand and separate, a band of exine is produced external to a thin foundation layer of tripartite lamellae. Dense globules assemble evenly throughout the locule, and these are incorporated progressively onto the spore surface to form the perine external to the exine. On the distal spore surface, the intine forms internally, while the spiny perine ornamentation is assembled. The exine is at least partially extrasporal in origin, while the perine is derived exclusively from outside the spore. Across the proximal surface of the polar spores, an aperture begins formation at the onset of spore development and consists of an expanded intine, an annulus, and a central pad with radiating fibers. This complex aperture is elastic and enables the proximal spore surface to cycle between being compressed (concave) and expanded (rounded). In addition to providing a site for water intake and germination, the elastic aperture is likely involved in desiccation tolerance. Based on the current phylogenies, the ancestral plant spore contained an aperture, exine, intine, and perine. The reductive evolution of liverwort and hornwort spores entailed the loss of perine in both groups and the aperture in liverworts. This research serves as the foundation for comparisons with other plant groups and for future studies of the developmental genetics and evolution of spores across plants.

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Section: Introductionmentioning

confidence: 99%

Sporogenesis in Physcomitrium patens: Intergenerational collaboration and the development of the spore wall and aperture

Renzaglia

Ashton

Suh

2023

Front. Cell Dev. Biol.

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Is there a tapetum in the hornwort capsule? Evidence from the sporogenesis of Phaeoceros

Filin,

Platonova

2024

Botanical Journal of the Linnean Society

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The tapetum is an important tissue in the sporangia of tracheophytes that provides nutrition for developing spores and participates in sporoderm construction, but the data on the tapetum in the sporangia of bryophytes and, in particular, hornworts, are contradictory. Some investigators considered the capsule wall and pseudoelates a tapetum in hornworts, but others suppose that the tapetum is absent in hornwort capsules at all. The structure of the sporocytes and spores, pseudoelaters, the lining layer of the capsule wall, and the outer layer of the columella of Phaeoceros laevis were studied at successive developmental stages by light, fluorescence, and transmission electron microscopy. We revealed that sporocytes accumulate carbohydrates that are required for the construction of the sporoderm and the storage of nutrients in mature spores before the formation of a special wall. Such a feature significantly distinguishes hornworts from mosses and angiosperms. Pseudoelaterocytes and pseudoelaters do not possess any ultrastructural features, indicating that they provide the sporocytes and spores with nutrition. Cells of the lining layer of the capsule wall and the outer layer of the columella do not possess characteristic ultrastructural features of secretory tissue at any developmental stage (in contrast to the moss tapetum), but they apparently participate in the transfer of nutrients in the capsule locule from the foot at the time the sporocytes are actively growing and accumulating nutrients. We accept the strict interpretation of the tapetum as a tissue that lines the capsule locule and has the specialized ultrastructure characteristic of the secretory tissues. Therefore, contrary to the opinion of some researchers, we believe that neither pseudoelaters nor the lining layer of the capsule wall should be considered a tapetum. Columella cells have a structural specialization for upward transport of assimilates, and they should not be regarded as a tapetum. We suppose that tapetum was absent in the common ancestor of the hornworts as well as in the common ancestor of embryophytes.

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Ultrastructure and development of sporoderm in Andreaeobryum macrosporum Steere & B.M. Murray (Andreaeobryopsida)

Cited by 2 publications

References 24 publications

Sporogenesis in Physcomitrium patens: Intergenerational collaboration and the development of the spore wall and aperture

Sporogenesis in Physcomitrium patens: Intergenerational collaboration and the development of the spore wall and aperture

Is there a tapetum in the hornwort capsule? Evidence from the sporogenesis of Phaeoceros

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