Background info on Physco biology and culture

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Physcomitrella patens is a monoecious moss, which requires simple growth conditions for the completion of its life cycle. Moss gametophytes exist in two morphologically distinct forms: the juvenile filamentous tissue called protonema and the adult leafy tissue called gametophore. However, the molecular mechanism for the transition from the juvenile (protonema) to the adult (gametophore) stage is not precisely known.

P. patens life cycle

Prigge Dev 2010 Fig. 2

P. patens life cycle. (A) A haploid spore germinates into (B) chloronemal cells, which continue to grow and differentiate into (C) caulonemal cells.

(D) Gametophores, or shoots, emerge off protonemal filaments and are ultimately anchored by rhizoids that grow by tip growth from the base of the gametophore.

(E) At the apex of the gametophore, both female, archegonia (arrows), and male, antheridia (arrowheads), organs form.

A motile flagellate sperm fertilizes the egg and the (F) sporophyte (marked with a bracket) develops at the apex of the gametophore.

Here is another good site that show the Physco Lifecycle and various structures.

Some PO terms:

not an exhaustive list...

• brachycyte (PO:0030058): A plant cell that develops from a cell in a protonema and has a thick cell wall. Comments: A brachycyte is a drought tolerant cell that can act as a gemma and may give rise to a new plant. Cells of a protonema may develop into brachycytes under stress. May form a chain or be separated by tmema cells.

• chloronema cell (PO:0030001): A chlorenchyma cell that is part of a chloronema and has cross walls of adjacent cells that are perpendicular to the protonema axis. Comments: A chloronema cell contains many well-developed chloroplasts.

• caulonema cell (PO:0030002): A chlorenchyma cell that is part of a caulonema and has cross walls of adjacent cells that are oblique to the protonema axis. Contains fewer chloroplasts.

• caulonema meristematic apical cell (PO:0030081): A protonema meristematic apical cell that is part of a caulonema. The chloronemata to caulonemata transition is controlled by plant hormones- mainly auxins

• gametophore (PO:0030018): A shoot system that consists of the shoot axes and non-vascular leaves of a plant in the gametophytic phase. The gametophore has non-vascular leaflets.

• Paraphysis (PO:0030070): A slender multicellular trichome that grows between the gametangia. Comment: Usually multiseriate. Found in bryophytes and pteridophytes,

• protonema (PO:0030003): A portion of chlorenchyma tissue that develops directly from a spore and grows by division of an apical cell to form filaments that are one cell wide and dicotomously branching.

• tmema cell (PO:0030059):A plant cell at the base of a gemma or adjacent to a brachycyte that breaks down to allow abscission of the gemma or brachycyte. Comments: May be a single cell adjacent to a brachycyte or part of a portion of tmema tissue.

Useful references:

• Rensing, et al. (2008). The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants. Science, 319, 64-69. (link)

• Wolf, L., Rizzini, L., Stracke, R., Ulm, R., and Rensing, S. A. (2010). The Molecular and Physiological Responses of Physcomitrella patens to Ultraviolet-B Radiation. Plant Physiology, 153, 1123 -1134.(link)

• Prigge, M. J. and Bezanilla, M. (2010). Evolutionary crossroads in developmental biology: Physcomitrella patens. Development, 137, 3535 -3543. (link)

• Cui, et al (2011). Proteome analysis of Physcomitrella patens exposed to progressive dehydration and rehydration. Journal of Experimental Botany. link

• Nishiyama,et al. (2003). Comparative genomics of Physcomitrella patens gametophytic transcriptome and Arabidopsis thaliana: Implication for land plant evolution. PNAS, 100, 8007 -8012. (link)