If you are experiencing problems downloading PDF or HTML fulltext, our helpdesk recommend clearing your browser cache and trying again. If you need help in clearing your cache, please click here . Still need help? Email help@ingentaconnect.com

Development of multicellular spores in the hornwort genus Dendroceros (Dendrocerotaceae, Anthocerotophyta) and the occurrence of endospory in Bryophytes

$39.00 plus tax (Refund Policy)

Buy Article:

Abstract:

Dendroceros is a clearly-defined tropical genus readily differentiated from other hornworts in that it grows on tree bark and leaves, and produces green multicellular spores. To further understand hornwort morphological diversity, we conducted a comprehensive ultrastructural investigation of post-meiotic development of multicellular spores in two species of Dendroceros. Following meiosis, unicellular spores remain in tetrads, expand to 60–75 μm in diameter, and fill the intracapsular space. At this stage, the spore wall consists of a highly convoluted homogeneous electron-opaque outer exine and narrow fibrillar inner exine. The single chloroplast is randomly organized with patches of pyrenoid precursors and poorly-differentiated thylakoids. With successive divisions, the solitary chloroplast differentiates into the large, star-shaped organelle with a distinct pyrenoid typical of mature gametophyte cells. Concomitant with these changes and an increase in cell number is a decrease in cell size, and an increase in cell content, especially protein storage bodies in vacuoles. There is no precise pattern of cell division and multicellular spores vary in shape and cell number, assuming the size and shape of the space in which they develop. Basipetal differentiation of multicellular spores is completed where the sporophyte emerges from the long involucre. Our study points to a novel hypothesis on the evolution of precocious endospory in epiphytic and epiphyllous hornworts. Because cell organization and organelle substructure undergo dramatic transformations during cell cycles, we speculate that endosporic and precocious divisions are a means to protect the nascent spore while it develops the biochemical and structural machinary to withstand drying. Therefore, we view the condition in Dendroceros, the only desiccation tolerant hornwort, as a feature directly related to this capability. As in Dendroceros, epiphytism and precocious endospory exist together in the leafy liverworts of the Porellales and several moss clades, also suggesting that desiccation tolerance may play a role in this co-occurrence.

Keywords: DENDROCEROS; ENDOSPORY; HORNWORTS; MULTICELLULAR SPORES; PRECOCIOUS GERMINATION

Document Type: Research Article

DOI: http://dx.doi.org/10.1127/0029-5035/2010/0091-0301

Publication date: November 1, 2010

More about this publication?
  • Nova Hedwigia is an international journal publishing original, peer-reviewed papers on current issues of taxonomy, morphology, ultrastructure and ecology of all groups of cryptogamic plants, including cyanophytes/cyanobacteria and fungi. The half-tone plates in Nova Hedwigia are known for their high quality, which makes them especially suitable for the reproduction of photomicrographs and scanning and transmission electron micrographs.
  • Editorial Board
  • Information for Authors
  • Subscribe to this Title
  • ingentaconnect is not responsible for the content or availability of external websites
Related content

Tools

Favourites

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more