Difference between revisions of "POC Conf. Call 5-03-11"
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==Conductive cells and tissues== | ==Conductive cells and tissues== | ||
Revision as of 17:29, 27 April 2011
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:
Conductive cells and tissues
THIS PART IS STILL UNDER CONSTRUCTTION
axial cell
First we need to address the definition of axial cell, as it was written with angiosperms in mind.
axial cell (PO:0000081): A vascular cell derived from the fusiform cambial initial and oriented with its longest diameter parallel with the main axis of stem or root. [source: ISBN:0471245208]
Comment: These cells make up the axial system, also known as vertical or longitudinal system.
We cannot define axial cell as a vascular cell, because the term vascular cell doesn't exist, and it includes non-conductive cells such as fibers. Also, not all cells that are currently under the category axial cell are derived from a fusiform initial.
Is axial cell the best name for this term? The phrase "axial system" is already used to describe the vascular tissue in wood (in contrast to the radial system), so "axial cells" might be automatically associated with that system.
Should this category include only conducting cells, or other types (like fibers and stereids). What about collenchyma cells?
At the bryophyte term meeting on 4-25-2011 (RW and MAG present), we decided that axial was not the correct term to use to describe all of the elongated cells found in a plant. They are different cell types and have different origins, so they should not all be grouped together.
Existing children of axial cell:
sieve tube member (PO:0000289, alt: PO:0000286)
phloem fiber (PO:0004519)
xylem element (PO:0000273)
>tracheary element (PO:0000273)
>>tracheid (PO:0000301)
>>vessel member (PO:0002003)
>xylem fiber (PO:0000274)
>>fiber tracheid (PO:0000355)
>>libriform fiber (PO:0004520)
>>septate fiber (PO:0004521)
New proposed hierarchy (children of plant cell):
hydroid (new term)
leptoid (new term)
vascular cell (new term)
>sieve tube member
>tracheary element
>>tracheid
>>vessel member
fiber cell (new term)
>phloem fiber cell
>xylem fiber cell
>other kinds of fiber cells
ground tissue cell
>stereid (new term)
Proposed definitions:
fiber cell:
vascular cell:
New terms for bryophytes:
hyrdoid (PO:0025032):: An elongate, water conducting cell that is dead at maturity, with tapered ends that are thin and partially hydrolyzed, that lacks specialized wall thickenings or lignin. [source: ISBN:0962073342 (Crum), ISBN:9780717810073]
Comment: Occurs in the gametophytic phase of a plant life cycle.
Proposed def.: A plant cell that is dead at maturity,lacks specialized wall thickenings or lignin, and has tapered ends that are thin and partially hydrolyzed.
Comment: Hydroids are water conducting cells found only in bryophytes in the gametophytic phase and in the seta in the sporophytic phase. [source: ISBN:0962073342 (Crum), ISBN:376821110 (Hebant)]
part_of hydrome
leptoid (PO:0025033): A food conducting cell associated with hydroids that resembles the sieve elements of some seedless vascular plants. [source: ISBN:962073342, ISBN:9780717810073]
Comment: Occurs in the gametophytic phase of a plant life cycle.
Proposed def.: A plant cell that resembles in structure the sieve elements of some seedless vascular plants. [ISBN:0962073342, ISBN:376821110]
Comment: A food conducting cell found only in bryophytes in the gametophytic phase and in the seta in the sporophytic phase. Food conducting cells in bryophytes range from conducting parenchyma cells that are indistinguishable from other parenchyma cells to leptoids sensu strictu that are structurally comparable to sieve elements in vascular plants, including many intermediate forms. The term leptoid is used for cells that are distinguishable from parenchyma cells, whether they be intermediate or leptoids sensu strictu.
part_of leptome
stereid (new term, PO:0025298): A ground tissue cell with thickened cell walls. [ISBN:0962073342, ISBN:376821110]
Comment: Found only in bryophytes in gametophore axes or leaves. Functions in support rather than conduction. May or may not retain a living protoplast at maturity.
part_of stereome
conductive tissue for bryophytes and vascular plants
vascular tissue
For vascular plants, we have the class:
portion of vascular tissue (PO:0009015): A portion of plant tissue that has parts xylem and phloem. [APweb:Glossary]
Comment: Functions in conduction and support. In the stem it is often found as a stele, surrounded by the cortex and surrounding the pith.
part_of vascular bundle (which is part_of vascular system)
This is okay, but suggest that we make it a child of the new class portion of axial tissue (see below), and also change definition to include xylem or phloem.
Proposed definition: A portion of axial tissue that has as parts tracheary elements or sieve tube members and is part of a vascular system.
Comment: Functions in conduction and support. In shoot axes, vascular tissue is often found as part of a stele or may occur as scattered vascular bundles. May include other types of tissue, such as fibers.
part_of vascular system (should add vascular system participates_in sporophytic phase)
currently part_of vascular bundle. Removed this relation, because it is not true for all plants. Also vascular bundle is now a portion of vascular tissue, so it can't be part_of.
children of vascular tissue:
hydathode (PO:0005660) - A structural modification of vascular and non-vascular tissues, usually in a leaf, that permits the release of water through a pore in the epidermis. [GR:pj, ISBN:0080374913]
Should be is_a cardinal organ part. Do hydathodes ever occur on stems or branches, or are they always part of phyllomes?
proposed definition: A cardinal organ part that releases water through a pore.
Comment: Usually found on leaves. Hydathodes may have one or more pores that appear to be incompletely developed stomata that lack the ability to open and close. Generally, hydathodes are located at the end of a minor vein. In many plants, hydathodes includes a portion of thin-walled parenchyma between the tracheary elements and the pore, known as an epithem. In some plants, hydathodes are associated with secretory tissue.
leaf vein (PO:0005417) - see more below details below
phloem (PO:0005417): A portion of vascular tissue whose principal function is conducting organic substances. [GR:pj]
proposed definition: A portion of vascular tissue that has as parts sieve tube members.
Comment: Functions in the conduction of organic substances in vascular plants.
metaphloem (PO:0006076): Part of the primary phloem that differentiates after the protophloem and before the secondary phloem, if any of the latter is formed.
proposed definition: A portion of phloem tissue that is the part of a primary phloem that differentiates after the protophloem and before the secondary phloem, if any of the latter is formed.
protophloem (PO:0006077): The first-formed elements of the primary phloem.
proposed definition: A portion of phloem tissue that has as parts the first-formed elements of the primary phloem.
tracheid bar (PO:0019026): A distinct ring-like structure, composed of tracheid cells, which surrounds the hilum of some taxa e.g., Phaseolus, and forms a groove in the surface of the pericarp (immediately adjacent to the hilum). [ISBN:0080280293]
-should be is_a xylem
xylem (PO:0005352): A portion of vascular tissue composed of (that has as parts) xylem elements.
vascular bundle (PO:0005020): A unit strand of the vascular system containing the vascular tissues, xylem and phloem. In addition vascular cambium is often present. [GR:pj]
This currently is_a portion of plant tissue. Should be is_a portion of vascular tissue.
proposed definition: A portion of vascular tissue that is a unit strand of the vascular system and has as part xylem or phloem.
Comment: Usually contains both xylem or phloem. May also contain other types of tissue such as plant fibers or vascular cambium. May also contain portions of ground tissue.
part_of vascular system
New children of plant tissue:
hydrome: A portion of axial tissue that has as parts hyrdoids.
Comment: Found in bryophytes, in the center of a non-vascular shoot axis such as a gametophore or seta, or in the midrib of a non-vascular leaf. Often surrounded by leptome. May function in water conduction and support, similar to xylem in vascular plants.
Synonyms: hydrom, leptoxylem (Hebant)
leptome: A portion of axial tissue that has as parts leptoids.
Comment: Found in bryophytes, in non-vascular shoot axes such as a gametophore 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)
central strand: A unit strand of axial 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
stereome: A portion of axial 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.
portion of plant fiber: Currently fibers are plant cell types, but they should also be a tissue type.
Proposed definition: A portion axial tissue that has as parts fiber cells.
Comment: Contains elongated, lignified fiber cells that are dead at maturity.
Need to create a term fiber cell that is_a sclerenchyma cell (and also add sclerid)
phloem fiber: A portion of plant fiber that has as parts phloem fiber cells.
xylem fiber: A portion of plant fiber that has as parts xylem fiber cells.
leaf vein, midrib, costa
- leaf vein (PO:0020138): A strand of vascular tissue in the leaf blade.
is_a portion of vascular tissue; part_of leaf vascular system
This term only applies to vascular leaves, and should be renamed vascular leaf vein.
proposed definition, vascular leaf vein (PO:0020138): A strand of vascular tissue that is part of a leaf lamina in a vascular leaf.
part_of leaf vascular system, part_of leaf lamina
- Suggest new term primary leaf vein: A vascular leaf vein that originates from the base of a leaf lamina where it attaches to the petiole or to the shoot axis if no petiole is present.
Comment: A leaf may have more than one primary vein. The central primary vein is the midvein.
- midvein (PO:0020139): The central, and usually the most prominent, vein of a leaf or leaf-like organ. [source: APWeb:Glossary]
Since midvein is_a leaf vein, it should say just "leaf" instead of "leaf or leaf-like organ". Suggest we rename it vascular leaf midvein to distinguish it from costa.
proposed definition of vascular leaf midvein: A primary leaf vein that is the central vein of a leaf lamina in a vascular leaf.
Comment: Often the most prominent vein of a vascular leaf.
broad synonyms: mid rib, midrib, mid-rib
related synonym: costa, Hickey and Peterson 1978 doi:10.1139/b78-128
- Moss Ontology has requested the term midrib for bryophytes. It is often called a costa.
Proposed definition for costa:' A central strand that is part of a non-vascular leaf.
Comment: Found in bryophytes, especially mosses.
part_of non-vascular leaf
broad synonyms: mid rib, midrib, mid-rib
Refs:
Sperry 2003, IJPS; Hebant 1977;
Sporangium parts
This is continued from our discussion at the POC_Conf._Call_3-8-11
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).
