POC Conf. Call 5-10-11

POC meeting, Webex Conference Call; Date: Tuesday May 10th, 2011 10am (PDT)

In attendance:

POC members:

Absent:

Collaborators:

Acceptance of the minutes from the POC_Conf._Call_5-03-11?

Issues arising from previous meetings:

Review of apical cell (PO:0030007) and its descendents

Postponed until next meeting.

At the POC meeting on 4/28/11, we decided to name this term meristematic apical cell

Proposed def.: A single meristematic cell at the tip of a shoot axis apex, leaf apex, root apex or thallus apex, in a plant structure where apical growth occurs.

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 may be established upon germination of a spore or upon the first cell division of an embryo or later.

is_a meristematic cell, sibling to initial cell

See: http://www.anbg.gov.au/bryophyte/case-studies/apical-cells.html

There was an extensive discussion last week and the week before about whether we should keep the term 'apical cell' to refer to the very tip or apical cell in an angiosperm leaf or other structure. The problem of adding a generic term for an apical cell is that it would cause confusion. Additionally is there really a single cell at the tip of a vascular leaf? For cells at the leaf apex (PO:0020137) and leaf tip (PO:0025142), we can use the existing PO terms. We decided to go with the proposed changes below and perhaps reconsider the issue of general term 'apical cell' in the future.

To ensure clarity, we should append the names of the child terms with 'meristematic' in their names, except for embryonic apical cell.

We could use always_in and never_in taxon relations to help clarify which taxa these are from

New proposed definition: A single meristematic cell at the tip of a plant structure where apical growth occurs.

Comment: Occurs in only bryophytes and some pteridophytes, at the tip of a shoot axis apex, leaf apex, root apex, thallus apex, or protonema. This term is only used when 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 may be established upon germination of a spore or upon the first cell division of an embryo or later.

New terms and definitions for apical cells

The definitions for the descendents of apical cell (listed below) were approved, pending approval of final definition of apical cell. See POC_Conf._Call_4-26-11#apical_cell for more details.

gametophytic apical cell (PO:0030014) > gametophytic meristematic apical cell

sporophytic apical cell (PO:0030015) > sporophytic meristematic apcial cell

thallus apical cell (PO:0030025) > thallus meristematic apical cell

root apical cell (PO:0030008) > root meristematic apical cell

shoot apical cell (PO:0030009) > etc.

gametophore apical cell (PO:0030019)

leaf apical cell (PO:0030011)

non-vascular leaf apical cell (PO:0030013)

vascular leaf apical cell (PO:0030012)

shoot axis apical cell (PO:0030010)

gametophore axis apical cell (PO:0030023)

vascular shoot axis apical cell (PO:0030024)

seta apical cell (PO:0030016)

embryonic apical cell (PO:0025284, replaces PO:0004000)

Also need to add a term for protonema meristematic apical cell.

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.

Proposed definition: A plant life cycle phase (or a whole plant growth stage) that begins with fertilization or the division of a non-fertilized embryogenic cell.

Comment: During the sporophtyic phase, a plant may produce meiospores by meiosis. A whole plant in the sporophytic phase usually has twice the chromosome complement of a plant in the gametophytic phase, but may not in the case of apogamy or in vitro culture of haploid embryos.

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.

Proposed definition: A plant life cycle phase (or a whole plant growth stage) that begins with meiosis.

Comment: During the gametophytic phase, a plant may produce gametes by mitosis. In bryophytes and pteridophytes, a gametophytic phase may begin without meiosis by apospory. This usually occurs when damage to a plant in the sporophytic phase leads directly to the growth of a plant that is in the gametophytic phase but bears the chromosome complement that would normally be found in the sporophytic phase. A whole plant in the gametophytic phase usually has half the chromosome complement of a plant in the sporophytic phase, but not in the case of apospory.