PO terms for lateral meristems #437
Comments
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Revisions from POC meeting on 2-14-12: lateral meristem (PO:0020145) cambium (PO:0005597) vascular cambium (PO:0005598) cork cambium (PO:0005599) primary thickening meristem (PO:0005039) secondary thickening meristem (PO:0025414) root lateral meristem (PO:0006308) Also made root meristem (PO:0006085) an XP. shoot lateral meristem (PO:0006344) Original comment by: rlwalls2008 |
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Additional changes from 2-14-12: Secondary thickening meristems (PO:0025414) are found in roots of some monocots (Cheadle 1937, JSTOR:2471543), so this should be lateral meristem, rather than a shoot lateral meristem. inflorescence lateral meristem (PO:0009105) ear lateral meristem (PO:0009110) Will create separate tracker for inflorescence, ear, and tassel meristems, because they need a lot of fixing to get rid of multiple inheritance. Original comment by: rlwalls2008 |
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As agreed upon at the POC meeting on 2-14-12, I added the new terms: shoot axis cork cambium (PO:0025435): A cork cambium (PO:0005599) that is part of a shoot axis (PO:0025029). root cork cambium (PO:0025436): A cork cambium (PO:0005599) that is part of a root (PO:0009005). shoot axis vascular cambium (PO:0025437): A vascular cambium (PO:0005598) that is part of a shoot axis (PO:0025029). root vascular cambium (PO:0025438): A cork cambium (PO:0005599) that is part of a root (PO:0009005). Original comment by: rlwalls2008 |
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From the POC meeting on 2-21-12: Accepted revised definition of lateral meristem (PO:0020145): A portion of meristem (PO:0009013) tissue located parallel to the sides of a a shoot axis (PO:0025029) or root (PO:0009005) that participates in lateral growth (GO:xxxxxxx, requested). Definition of vascular cambium (PO:0005598) from 2/14/12 was okay. Revised comment to say: A vascular cambium produces cells in both directions, centrifugally and centrifically, leading to an increase in the cross-sectional area of a plant axis (PO:0025004). Definition of secondary thickening meristem (PO:0025414) was revised to encompass both roots and shoots: A lateral meristem (PO:0020145) that is not contiguous with an apical meristem (PO:0020144) and has a parts multiple layers of meristematic cells (PO:0004010). For clarity, we will add synonyms to the following terms: Also changed tassel lateral meristem to tassel inflorescence branch meristem (PO:0009107), similar to ear inflorescence branch meristem (see below). Other definitions from 2/14 were accepted as below. Original comment by: rlwalls2008 |
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Also added: stem secondary thickening meristem (PO:0025442): A secondary thickening meristem (PO:0025414) that is part of a stem (PO:0009047). [JSTOR:4354165] root secondary thickening meristem (PO:0025443): A secondary thickening meristem (PO:0025414) that is part of a root (PO:0009005). [JSTOR:2471543] Original comment by: rlwalls2008 |
lateral meristem (PO:0020145)
current def.: A meristem containing cells along the stem or root that first differentiate and function as members of a mature tissue system but then again take up meristematic activity.
proposed def.: A meristem located parallel to the circumference of a plant organ.
comment: Participates in lateral growth (GO:xxxx) of a plant organ, primarily shoot axes and roots. Contrast with apical meristem (PO:0020144).
root lateral meristem (PO:0006308)
current def.: Meristem of the root located parallel to the sides of the axis.
comment: Generally causes root thickening. Not to be confused with lateral root meristem (PO:xxx), which is the meristem of the lateral root.
This is just a cambium in the root, which also has vascular cambium and phellogen.
proposed new name and def.: root cambium: A cambium that is part of a root.
This terms has six annotations. These should be checked, because it is not obvious what some of them have to do with roots.
If we are going to have this term, maybe we should have root vascular cambium and root cork cambium, plus shoot axis vascular cambium and shoot axis cork cambium?
cambium (PO:0005597)
current def.: A lateral meristem, the cells of which divide mostly periclinally. [source: ISBN:0080374913]
proposed def.: A lateral meristem that has a part a single layer of cambial initial cells and their derivatives, arranged orderly in radial files. (Ref.: Esau)
comment: This term is applied to only two types of meristems: vascular cambium (PO:0005598) and cork cambium/phellogen (PO:0005599).
vascular cambium (PO:0005598)
current def.: A lateral meristem, the cells of which give rise to secondary xylem and phloem, leading to an increase in girth.
Current definition is okay, but needs minor changes.
proposed def.: A cambium that gives rise to secondary xylem and secondary phloem.
comment: Vascular cambium is located between the secondary xylem and secondary phloem and gives off cells in both directions by periclinal division, leading to an increase in girth of a plant axis.
cork cambium/phellogen (PO:0005599)
current def.: Lateral meristem which produces the phellem (cork) and the phelloderm.
proposed def.: A cambium that is part of a periderm and produces phellem (cork) and phelloderm.
comment: Cork cambium is located in a plant axis, between the phellem and phelloderm, and produces phellem toward the outside and phelloderm toward the inside.
primary thickening meristem (PO:0005039)
current def.: A meristem that develops from a peripheral zone of a shoot apical meristem and is responsible for the primary increase in thickness of a shoot axis.
comment: May appear as a distinct mantle like zone. Often found in monocotyledons.
Esau defines it as originating in the apical meristem, but Rudall's review shows that in some species, it is discontinuous with the SAM.
proposed def.: A lateral meristem that has a parts multiple layers of cells located near the shoot apical meristem.
comment: Contributes to primary thickening of the stem, adventitious root formation, and formation of linkages between the stem, leaf, and root vasculature. Contiguous with the shoot apical meristem in some species, but not all. Produces more or less distinct vascular bundles surrounded by ground tissue, as opposed to the more or less continuous xylem and phloem produced by a vascular cambium. A primary thickening meristem is a multi-layered structure, compared to the single layer of a cambium. Found in many monocotyledons.
secondary thickening meristem (new term)
proposed def.: A lateral meristem that is part of a shoot axis not contiguous with the shoot apical meristem and has a parts multiple layers of cells.
comment: Contributes mainly to formation of the body of a stem, but may also produce adventitious roots. May be continuous or discontinuous with the primary thickening meristem. Found in some monocot species of the Liliales and Asperigales.
Other types of lateral meristems:
PO has the terms shoot lateral meristem (PO:0006344), inflorescence lateral meristem (PO:0009105), ear lateral meristem (PO:0009110) and tassel merristem (PO:0009107), plus their subtypes.
Shoot lateral meristem is okay, but inflorescence lateral meristem and all the others are misleading. Inflorescence branches develop from apical meristems, not a lateral meristem.
There are three annotations on shoot lateral meristem and two on inflorescence lateral meristem that should be moved to shoot apical meristem.
inflorescence lateral meristem (PO:0009105)
current def.: The meristem which gives rise to the lateral structures of the inflorescence and contributes to their apical growth.
This should be called inflorescence branch meristem, and be a subtype of inflorescence meristem (PO:0000230), which should in turn be an apical meristem.
ear lateral meristem (PO:0009110)
current def.: The meristem that gives rise to the lateral structures of a maize ear.
This should be called ear inflorescence branch meristem, and be a subtype of inflorescence branch meristem (PO:0009105). Will need to add XP definitions to the different types of meristems so that they don't have dual parentage (e.g., ear inflorescence meristem XP of is_a inflorescence meristem and part_of ear inflorescence).
proposed def.: An inflorescence branch meristem that gives rise to the branches of an ear inflorescence.
Reported by: rlwalls2008
Original Ticket: obo/plant-ontology-po-term-requests/437
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