POC Conf. Call 5-03-11
POC meeting, Webex Conference Call; Date: Thursday April 28th, 2011 10am (PDT)
In attendance:
POC members:
Absent:
Collaborators:
Acceptance of the minutes from the POC_Conf._Call_4-28-11?
Items arising from previous meetings:
Plant Tissues
paraphyllium (PO:0030069)
Tiny filaments, scales or leaf-like structures scattered on the stems of some leafy bryophytes. Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition (MO definition)
Crum defines them as "Small green outgrowths formed between the leaves on stems and branches of some pleurocarps (mosses that produce archegonia and sporophytes laterally, rather than on the tips of their axes) and a very few leafy liverworts."
Schofield describes paraphyllia as outgrowths of the epidermis, but he also describes leaves that way.
Moss Ontology has paraphyllium listed as a plant organ, but they do not arise from the SAM as phyllomes do.
Proposed definition: A portion of epidermal tissue that is a small outgrowth from the epidermis between the leaves of a gametophore axis.
Comment: Paraphyllia are much smaller than leaves and may be filamentous, scale-like, or leaf-like. Found in pleurocarpous mosses and a few leafy liverworts.
is_a epidermis, part_of gametophore axis
The paraphyllia are the small, dark structures between the leaves.
paraphysis (PO:0030070)
Moss Ontology definition: Sterile, septate, usually uniseriate hairs intermixed with sex organs. Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition
From Parihar: sterile, slender filaments accompanying reproductive organs.
From Schofeld: filamentous sterile structures intermixed with the sex organs of most mosses
These are a kind of trichome
Proposed def.: A slender, usually uniseriate multicellular trichome that grows intermixed with the gametangia.
Comment: Found in bryophytes and pteridophytes, especially in mosses.
adjacent_to gametangium, plural: paraphyses; particpates_in gametophytic phase
axillary hair (PO:0030060)
Moss Ontology definition: A small filament in an axil consisting of one long terminal cell atop a basal stalk (also called club-hair). Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition
This is a type of trichome. Axillary trichomes may also be found in angiosperms, but they are different, so suggest we specify that this for hairs in gametophores.
Proposed def., gametophore axillary hair: A multicellular trichome consisting of one long terminal cell atop a basal stalk that grows in the leaf axil of a non-vascular leaf.
Comment: Found in pleurocarpous mosses. Form in the axils of leaf primordia, and may disappear when the gametophore is mature.
synonym: club-hair; part_of gametophore
rhizoid (PO:0030071)
Moss Ontology definition: Filamentous tissue protruding from the gametophore stem with a rooting function.
Rhizoids may also grow from thalli. They arise from an epidermal intial (the rhizoid initial), and so are like trichomes. Like trichomes, they may be uni- or multicellular
Proposed def.: A trichome that is part of a plant in the gametophytic phase and has positive gravitropism.
Comment: Found in bryophytes and pteridophytes growing from the epidermis of the lower surface of a gametophore or thallus. May be multicellular or unicellular. Usually serves to anchor the plant to the substrate.
Should we say: May also arise directly from a protonema?
develops_from rhizoid initial, participates_in gametophytic phase
tmema (PO:0030061)
Moss Ontology definition: An abscission cell at the base of a gemma (vegetative propagule). Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition
Their definition defines a cell type, but they have tmema as a tissue type. It would be the tissue composed of tmema cells
Proposed def.: A portion of plant tissue that has as parts tmema cells.
Comment: Found in bryophytes at the base of a gemma. Participates in abscission of the gemma.
participates_in gametophytic phase, has_part tmema cell
antheridium jacket layer (PO:0030053)
Moss Ontology definition: A layer of cells that surrounds the spermatogenous tissue that cannot give rise to sperm.
The term jacket layer is also used for the outer layer of sporangia. Suggest naming this term antheridium wall or antheridium jacket layer
proposed definition: A portion of plant tissue that is a single layer of cells on the outside of an antheridium.
Comment: Cells in the antheridium jacket layer surround the inner spermatogenous cells and do not give rise to sperm cells.
part_of antheridium; synonym: sterile jacket layer, antheridium wall
hydrome
proposed definition: A portion of plant tissue that has as parts hyrdoids.
Comment: Found in bryophytes, in the center of a non-vascular shoot axis such as a gametophore axis or seta, or in the midrib of a non-vascular leaf. Often surrounded by leptome. May function in conduction of water and minerals and in support, similar to xylem in vascular plants.
Synonyms: hydrom, leptoxylem (Hebant)
leptome
proposed definition: A portion of plant tissue that has as parts leptoids.
Comment: Found in bryophytes, in non-vascular shoot axes such as a gametophore axis or seta, or in the midrib of a non-vascular leaf. Often surrounding a central hydrome. May function in the conduction of organic substances, similar to phloem in vascular plants.
Synonyms: leptom, leptophloem (Hebant)
stereome
proposed definition: A portion of plant tissue that has as parts stereids.
Comment: Found in bryophytes.
From Hebant: A typical moss stem comprises, from the outside to the inside, an epidermis with a thin cuticle but no stomata, an outer cortex which frequently consists of supporting ells with thickended walls ("stereids"), an inner cortex of thin-walled conducting cells, and, in a number of species, a central strand of hydroids.
central strand
proposed definition: A unit strand of plant tissue that has as part hydrome or leptome.
Comment: Often contains both hydrome and leptome. Found in bryophytes located in the center of non-vascular shoot axes such as a gametophore axis or seta, or in the costa of a non-vascular leaf.
synonyms: conducting strand, central cylinder
Parts of sporangium
This is continued from our discussion at the POC_Conf._Call_3-8-11
Moss Ontology has requested the terms archesporium, amphithecium, and endothecium.
For background, see Summary of sporangium development in various non-angiosperm taxa.
Currently classes like exothecium, endothecium, primary parietal cell layer and tapetum are part of anther wall (PO:0000002). However, these layers and their constituent cell types can be part of any sporangium, not just an anther. Proposed making them part of a general class sporangium wall (as we did for parts of leaf). Tissues that are in all sporangia can be a child of this class. We could make specific children for anther exothecium, anther endothecium, etc.
- At the POC_Conf._Call_3-8-11, we agree that anther lobe should be narrow synonym of pollen sac.
- At the POC_Conf._Call_4-28-11 we agree to rename theca anther theca.
- At the POC_Conf._Call_3-8-11, we agree that anther theca (PO:0009069) should be is_a collective organ part structure, part of anther, has_part pollen sac.
- At the POC_Conf._Call_4-28-11 we discussed making anther theca a child of sporangium theca.
- At the POC_Conf._Call_3-8-11, we agree that microsporocyte (PO:0020047) should be part_of microsporangium instead of part_of pollen sac, so it is more general.
Also agreed to add a new term "sporocyte", parent to megasporocyte and microsporocyte, and also as a class for the sporocytes in homosporous plants like mosses. [We already have the term sporocyte, but the definitions of the sporocyte terms need a little work.]
