POC Conf. Call 4-12-11
POC meeting, Webex Conference Call; Date: Tuesday April 12th, 2011 10am (PDT)
In attendance:
POC members:
Absent:
Collaborators:
Acceptance of the minutes from the POC_Conf._Call_4-5-11?
Items arising from last week's meeting:
in vitro plant structures
embryo (PO:0009009)
current definition: A whole plant in the post-zygotic stage that does not yet consist of fully differentiated tissues.
Comment: Adventitious embryos and somatic embryos do not arise from zygotes. Cultured embryos (PO:0000010), including haploid embryos, are in vitro plant structures. Embryos occur prior to germination in vascular plants.
This is not really consistent with the fact that we have tissues like embryonic epidermis and embryonic cortex.
Logically, an embryo could be treated like a sporophyte or gametophyte, that is, as a cross-product of whole plant and the appropriate life cycle phase. However, since we don't have embryonic phase yet, and since so much research is done on embryos, it may be appropriate to keep the class embryo, and pre-compose the cross-product once we have embryonic phase.
Proposed definition: A whole plant in the sporophytic phase that is contained in an archegonium or a seed.
Comment: The embryo is a whole plant after fertilization (post-zygotic) and before emergence from the archegonium (for bryophytes and pteridophytes) or seed germination (for seed plants). Embryos that arise through apogamy, adventitious embryos, and somatic embryos do not arise from zygotes. Cultured embryos (PO:0000010), including haploid embryos, are in vitro plant structures.
Do we want to keep the comment that cultured embryos are in vitro plant structures?
Haploid embryos develop into haploid sporophytes, even if those sporophytes may be sterile. This happens naturally in many ferns and sometimes in bryophytes (apogamy - when a gametophyte gives rise to a sporophyte without syngamy). The reverse also happens (apospory -- when a sporophyte gives rise to a gametophyte without meiosis).
However, haploid embryos cannot be considered in the sporophytic phase (as it it defined now), since they are not the product of fertilization. Suggest that we rework the definition of sporophytic phase with a comment about apogamy.
We could add zygotic and haploid embryo as children of embryo.
gametophytic phase and sporophytic phase
sporophytic phase (PO:0028002)
Current definition: A plant life cycle phase that is the product of fertilization. [source: POC:rw]
Comment: During the sporophtyic phase, a plant may produce meiospores by meiosis.
gametophytic phase (PO:0028003)
Current definition: A plant life cycle phase that arises through meiosis. [source: POC:rw]
Comment: During the gametophytic phase, a plant may produce gametes by mitosis.
portion of plant tissue (PO:0009007)
current definition: A plant structure that has as its parts multiple cells and is a proper part of an organ. [source: POC:curators, TAIR:lr]
Comment: These cells are organized into a structural unit, and may include an intercellular matrix.
There are several problems with this definition:
-It does not exclude cardinal organ parts.
-Saying that it is a proper part of an organ does not work for cultured callus of for tissues in plants that don't have any organs (like a protonema or thallus).
Proposed definition: A plant that has as its parts multiple cells and is a proper part of a plant and...
Comment: These cells are organized into a structural unit, and may include an intercellular matrix.
embryonic plant structures
Definition of embryonic plant structure:
embryonic plant structure (PO:0025099): A plant structure that is part of an embryo.
Comment: Includes organs, tissues and cell types that are unique to embryos, not plant structures that can occur in both embryos and mature plant structures.
Changed definition from "proper part of" to "part of", so it would be consistent with the intersection of term. Think part_of is better anyway, because technically an embryo is an embryonic plant structure.
Some terms were left as is_a children of embryonic plant structure:
coleoptile (PO:0020033): A tubular embryonic structure developed at the junction of the cotyledonary sheath with the seedling axis, and surrounding the plumule of a monocot embryo or seedling.
embryo proper (PO:0000001): An embryonic plant structure that is the body of a developing embryo attached to the maternal tissue in an ovule by a suspensor.
scutellum (PO:0020110): An embryonic plant structure that is a more or less shield-shaped and absorptive portion of an embryo of Poaceae.
suspensor (PO:0020108): An embryonic plant structure at the base of an embryo that develops from a basal cell and connects an embryo proper to the wall of a megagametophyte.
New definitions for embryonic plant cells and tissues
Both now have cross-product definitions, and no asserted is_a children
embryonic plant cell (PO:0025028): A plant cell that is part of an embryo.
is_a embryonic plant structure, intersection_of: is_a plant cell, intersection_of: part_of embryo
Made apical cell (PO:0004000, now embryonic apical cell) is_a apical cell part_of embryo (still dev_from zygote). Should probably obsolete and replace with new term to avoid confusion
Made basal cell (PO:0002002, now embryonic basal cell) is_a plant cell, part of embryo (still dev_from zygote)
Made hypophysis (PO:0020109, now embryonic hypophysis) is_a plant cell, part_of embryo.
(portion of) embryonic plant tissue (PO:0025233): A portion of plant tissue that is part of an embryo.
is_a embryonic plant structure, intersection_of: is_a portion of plant tissue, intersection_of: part_of embryo
coleorhiza (PO:0020034), embryo cortex (PO:0005014), embryo epidermis (PO:0005015), embryonic shoot apical meristem (PO:0006362), epiblast (PO:0020036), scutellar epithelium (PO:0008048), and scutellum epidermis (PO:0006049) are now inferred children of embryonic plant tissue.
Technically, we could get rid of the is_a embryonic plant structure relation for both, because it would be inferred, but is makes it easier to work with the reasoner off when the relations are there.
Here is a picture of some plant tissues, to show how it works:
Proposed changes/questions for structures that were is_a embryonic plant structure:
embryonic leaf (PO:0006338): One of the first few leaves to develop from the embryonic shoot apical meristem [GR:pj].
Is this an embryonic plant structure, that is, is it always part of the embryo?
Proposed definition: A vascular leaf that is one of the first few leaves to develop from the embryonic shoot apical meristem and is part of an embryo.
is_a vascular leaf, part_of embryo (need to confirm part_of relation)
embryonic root (PO:0000045): An embryonic plant structure that is a root that is initiated in a developing embryo. [TAIR:ki]
Propose that this should be is_a root instead of is_a embryonic plant structure, b/c it is not necessarily part of an embryo.
Proposed definition: A root that is initiated in a developing embryo.
radicle (PO:0020031): The radicle is the basal continuation of the hypocotyl in an embryo and gives rise to the root system of the adult plant; sometimes more or less abortive. is_a embryonic root [APWeb:Glossary]
Proposed definition: An embryonic root that is the basal continuation of a hypocotyl in an embryo and may develop into the root system of an adult plant.
Comment: Sometimes abortive.
remove part_of embryo axis.
hypocotyl (PO:0020100): The part of the stem below the cotyledonary node and transitional to a root, found in a young sporophyte. [APWeb:Glossary]
currently is_a cardinal organ part, propose is_a stem internode (we didn't have this term before but do now)
Proposed definition: A stem internode that is the part of a stem below the cotyledonary node and transitional to a root.
is_a stem internode
epicotyl (PO:0020035): The first internode of a stem above the hypocotyl. In literature also used for the entire embryonic axis, consisting of several internodes, above the cotyledonary node. [APWeb:Glossary]
currently is_a embryonic plant structure, propose is_a stem internode (PO:0005005). Also, the second part of the current definition only adds ambiguity. Need to define it more precisely.
Proposed definition: The first stem internode above a hypocotyl.
mesocotyl (PO:0020037): The internode between the cotyledon or cotyledons and the leaf or leaves at the next node of a young sporophyte.
This definition sounds like the same thing as an epicotyl. Should they be synonyms?
made is_a stem internode
hypocotyl-root junction PO:0004724: A cardinal organ part that is the part of an embryonic axis where the radicle joins the hypocotyl.
Moved to is_a cardinal organ part. Will automatically be is_a embryonic plant structure b/c it is part of embryonic axis. Is this accurate? The hypocotyl-root junction remains after germination.
plumule(PO:0020032): A somewhat differentiated terminal bud in several embryo types above the cotyledonary node, in which one or more internodes and leaves or scales can be discerned in a primordial stage.
made is_a terminal bud, part_of embryo
scutellar node (PO:0004708): The region in of an embryo axis between the primary root (enclosed in the coleorhiza) and the plumule (enclosed in the coleoptile) to which the scutellum is attached. [MaizeGDB:lv]
Sounds like it should be is_a stem node.
Proposed definition: A stem node that is the part of an embryo axis where the scutellum is attached.
Comment: A scutellum is attached to an embryo axis between the primary root (enclosed in the coleorhiza) and the plumule (enclosed in the coleoptile).
is_a stem node, part_of embryo axis
Collective plant structures:
vascular and non-vascular shoot systems
The Moss Ontology did not request these terms, but suggest adding them in order to classify shoot systems.
non-vascular shoot system: A shoot system that does not have as part vascular tissue.
comment: Does not have any xylem of phloem, but may have other conducting cells, such hydroids or leptoids. Can occur in both the gametophytic and sporophytic phases of non-vascular plants.
subsets for bryophytes
Could we use the relation "lacks_part"? Then we could define this class using intersection_of relations, which would be better. CL has used this (lack_plasma_membrane_part). Works better in OWL; translates into something like has_part exactly 0 (some Y).
Child of non-vascular shoot system will be gametophore (see below). A moss sprophyte could also be called a non-vascular shoot system. If we used the lacks_part relation and intersection_of relations, we could make gameotophore a child of shoot system, and the reasoner would infer it was a non-vascular shoot system.
Can't use participates_in gametophytic phase, because the sporophyte of a bryphyte doesn't have roots or vascular tissue.
vascular shoot system: A shoot system that has as part vascular tissue.
comment: Has xylem and/or phloem. Occurs only in the sporophytic phase of vascular plants.
participates_in sporophytic phase, has_part vascular system
If we accept these terms, suggest changing definitions of vascular leaf (PO:0009025) and non-vascular leaf (PO:0025075) to "A leaf that is part of a vascular/non-vascular shoot system. This would be better than the current definitions which reference their taxonomy (part of a vascular or non-vascular plant) and would help with reasoning.
root-bourne shoot system (PO:0004544) should be is_a vascular shoot system
gametophore
Definition supplied by Moss Ontology: The leafy moss plant. The gametophore is the adult form of the moss gametophyte and bearer of the sex organs (gametangia). Ref: Reski (1998): Development, genetics and molecular biology of mosses. Botanica Acta 111, 1-15.
Suggest is_a shoot system.
Proposed def.: A non-vascular shoot system that consists of the shoot axes and non-vascular leaves of a plant in the gametophytic phase.
participates_in gametophytic phase, develops_from gametophore bud
Comment: A gametophore is the leafy part of the gametophyte of mosses and leafy liverworts, excluding the protonema. Develop from buds that form on the protonema. Antheridia and archegonia arise on the gametophore.
subset for bryophytes
gametophore bud
The term "bud" has been requested: Def'n supplied by Moss Ontology: A structure produced by a caulonema and able to develop into a gametophore or a stem that includes an apical cell able to develop into a gametophore. The earliest recognizable stage of gametophore development. Ref: Bill and Nancy Malcolm (2006): Mosses and other Bryophytes, an illustrated glossary, second edition and altered by David Cove
Suggest a new term gametophore bud. This could be a child of bud (PO:0000055: An undeveloped shoot system).
Proposed def'n: A bud that develops into a gametophore.
Comment: Occurs in mosses and leaf liverworts. Develops from a caulonema cell in mosses.
participates_in gametophytic phase, has_part gametophore apical cell
synonym: brown bud
thallus
From Parihar: A simple vegetative plant body not differentiated into root, stem and leaf, and lacking vascular tissues.
From Schofeld: A flattened gametophore in which no leaf-like organs dominate the structure.
Saying a thallus is a gametophore implies that it is a shoot system and therefore a collective plant structure (CPS). As a CPS, it must have more that one organ. This is not always true for a thallus (sometime they branch, so you could say they have multiple axes, but it is a stretch. Maybe better to classify it as a whole plant.
proposed def: A whole plant in the gametophytic phase that has a flat growth form and no distinct organs.
Comment: A thallus is a gametophyte of liverworts and pteridophytes and develops from a short-lived protonema. Roughly two dimensional growth results from division of a single apical cell. Thalli may be ribbon or heart shaped or almost filamentous. Although there are no distinct organs, there may be tissue differentiation and dichotomous branching.
Add prothallium as a broad synonym of thallus and as a narrow synonym of whole plant.
Other gametophyte terms
We need to keep in mind terms for other types of gametophytes, such as the subterranean, heterotrophic gametophytes of some ferns. RW, DWS, and MAG will maintain a list of terms that we don't need to add yet, but may want to add as time allows or need demands. Can use this list, for example, for writing a renewal of things that still need to be done.
apical cell
Moss Ontology has requested the term apical cell. Apical growth in byrophytes is via division of a single cell at the tip of the shoot apical meristem. They also requested shoot apical cell and phyllid apical cell.
Non-seed vascular plants can also have an apical cell, that is, a single dividing cell at the apex of a root or shoot.
We already have the term apical cell (PO:0004000), which is an embryonic cell: "An embryonic plant cell that is the uppermost cell formed after the first division of the zygote." The embryonic apical cell can also be found in non-angiosperms. Suggest obsoleting PO:0004000 and replacing it with the new termembryonic apical cell for clarity, and using the name apical cell for the general class of apical cells described below.
Definition of apical cell from Esau: The single initial cell in an apical meristem of root or shoot. Characteristic of many lower vascular plants.
Definition of apical cell from Crum: A single cell at the tip of a stem, leaf, leaf or other structure that divides repeatedly to form new cells; also known as an apical intial.
Is apical cell more consistent with meristematic cell (A cell synthesizing protoplasm and producing new cells by division and with only a primary cell wall) or with initial cell (A meristematic cell that by division gives rise to two cells, one of which remains meristematic, while the other is added to the plant body)? Probably meristematic cell, because the apical cell can give rise to more than two cells (because it can have three or four cutting faces).
Proposed def. of apical cell: A single meristematic cell at the tip of a shoot axis apex, leaf apex, root apex, or thallus apex.
Comment: Occurs in bryophytes and some pteridophytes, where apical growth results from division of a single meristematic cell located at the tip of an apical meristem or plant organ, rather than from a population of meristematic cells located at the tip of an apical meristem. May be tetrahedral shaped, with three (in shoots) or four (in roots) cutting faces, or wedge shaped with two cutting faces (in non-vascular leaves or thalli). An apical cell is established upon the first cell division of an embryo or germination of a spore.
-note: the last sentence of the comment allows us to classify an embryonic apical cell as an apical cell.
Suggested ontology structure for the children of apical cell:
The dotted lines represent relations inferred by the reasoner.
Includes two ways of classifying: by structure and by gametophyte/sporophyte. Structural relations are asserted as is_a relations. The relations to gametophyte or sporophyte are inferred by the intersection_of terms.
New terms and definitions for apical cells
gametophytic apical cell: An apical cell that is part of a whole plant in the gametophytic phase.
Comment: Occurs in mosses and other bryophytes.
intersection_of: is_a apical cell, intersection_of: participates_in gametophytic phase
sporophytic apical cell: An apical cell that is part of a whole plant in the sporophytic phase.
Comment: Occurs in pteridophytes and the sporophyte of bryophytes.
intersection_of: is_a apical cell, intersection_of: participates_in sporophytic phase
thallus apical cell: An apical cell that is part of a thallus.
part_of thallus
root apical cell: A sporophytic apical cell that is part of a root apical meristem.
comment: Only occurs in the sporophytic phase of vascular plants.
part_of root apical meristem
shoot apical cell: An apical cell that is part of a shoot system.
comment: May occur in shoot axes or leaves of bryophytes or ferns.
part_of shoot system
gametophore apical cell: A shoot apical cell that is part of a gametophore.
comment: Occurs in the non-vascular shoot system of the gametophyte of mosses.
intersection_of: is_a shoot apical cell, intersection_of: part_of gametophore
leaf apical cell: A shoot apical cell that is part of a leaf apex.
comment: Occurs in the non-vascular leaves of bryophytes and the vascular leaves of some mosses. Only in plants where leaf growth is apical.
part_of leaf
non-vascular leaf apical cell: A leaf apical cell that is part of a leaf apex of a non-vascular leaf.
comment: Occurs in the non-vascular leaves of bryophytes, which grow by division of a single, wedge-shaped apical cell with two cutting faces.
part_of non-vasucular leaf; synonym: phyllid apical cell
vascular leaf apical cell: A leaf apical cell that is part of the leaf apex of a vascular leaf.
comment: Occurs in vascular leaves of some ferns in their sporophytic phase.
part_of vascular leaf
shoot axis apical cell: An apical cell at the tip of a shoot apical meristem.
Comment: Divides to produces leaf initial cells and other stem tissues.
part_of shoot apical meristem
gametophore axis apical cell: A shoot axis apical cell at the tip of a gametophore axis.
Comment: Occurs at the tips of the stems and branches of bryophytes.
part_of gametophore axis; synonym: cauloid apical cell, non-vascular shoot axis apical cell
vascular shoot axis apical cell: A shoot axis apical cell at the tip of a shoot apical meristem in a vascular shoot system.
Comment: Occurs in some ferns in their sporophytic phase.
part_of vascular_shoot system; synonym: fern shoot axis apical cell
Also:
embryonic apical cell (replaces PO:0004000): An apical cell that is part of an embryo and is the uppermost cell formed after the first division of the zygote.
Comment: For plants that grow via an apical cell in their sporophytic phase, the embryonic apical cell may remain meristematic throughout the plant's life.
