A delayed response on "POC observations so far"

[Sue Rhee]

give me the bottom line in three sentences or less.

thanks,
sue

On Wed, 8 Oct 2003, Vincent, Leszek wrote:

> Hi POC colleagues,
>
> Here's some 'bedtime reading'.
>
> Recently there was discussion about the representation of unisexual
> florets in a taxon which bears both functionally male & female florets
> in separate flowering structures e.g. adequate representation of monoecy
> in taxa such as Zea mays. Furthermore concern was raised about querying
> an ontology, involving a monoecious taxon, for the term gynoecium - that
> such a search should be able to retrieve gynoecium-related info.
> associated with the tassel as well as the ear as in Zea mays.
>
> Pankaj & possibly some others may recall that some of us visited this
> area sometime last year & the synthesis of that dialogue was recorded in
> the current ontology for Zea mays (freely available from
> plantontology.org). But to show you an example of the tentative solution
> to the challenge I've reproduced a portion of the representation below:
>
> organ
>   %tassel (functionally male inflorescence)
>     <pedicellate spikelet of tassel
>       <lower floret of pedicellate spikelet of tassel
>         <gynoecial tissue (abortive) of lower floret of pedicellate
> spikelet of tassel
>         <lodicules of lower floret of ....
>         <palea of lower floret of .....
>         <stamens of lower floret of ....
>       <lower glume of pedicellate spikelet of tassel
>       <upper glume of .....
>     <sessile spikelet of tassel
>       etc.
>   %lateral branch
>     <ear (functionally female inflorescence)
>       <pedicellate spikelet of ear
> etc....
>
> Yes, it is a little complex (view it via DAG-Edit for a clearer
> representation than that provided here) but it is my/our best attempt
> yet at capturing the biological complexity such that the true path rule
> is met for this biological reality in Zea mays. Furthermore, it should
> satisfy the query needs referred to above. Of course there may be other
> considerations that have since transpired...
>
> For me, as a botanist & plant systematist, I think it is a good solution
> because it captures the ontogenetic detail for these structures and it
> is also consistent with phylogenetic argument concerning these
> structures - and consequently should be applicable to taxa, other than
> Zea, where monoecy & dioecy is found.
>
> It is true that some folk may not (at first) appreciate the biological
> relevance of including both the androecium & gynoecium in both the
> tassel & ear. My attempt to cover that 'base' is provided in the
> definition for "floret". In this definition I spell out the ontogenetic
> reality of both the androecium & gynoecium being initially present in
> both the tassel & ear florets - hence their need to be included in both
> the tassel & lateral branch/ear nodes. It also draws attention to the
> putative phylogenetic necessity for such a representation. Implicitly
> what I'm practicing is that ontogenetic & phylogenetic information are
> both extremely important for inclusion in the application of the 'true
> path rule'.
>
> Here's the definition for floret (yes, it is detailed):
> "The floret is the individual flower of the Zea mays plant. In the grass
> family (Poaceae, alt. Gramineae) each floret is typically bisexual
> (perfect), possessing both an androecium and a gynoecium. Each floret
> typically has a pair of bracts, the lemma and palea, which subtend the
> floret. It is important to note that In Zea mays the florets of the
> 'tassel' are functionally male (the female component (gynoecium) having
> aborted early on in development). The florets of the 'ear' are
> functionally female (the male components (androecium) having aborted
> early on in development). The possession of functionally male and
> functionally female florets (or flowers) on the same plant is a
> condition called monoecy. While Zea mays is functionally monoecious, the
> presence of both androecial and gynoecial tissue in the early stages of
> floret ontogeny is phylogenetically significant. Consequently, the
> androecium is represented in the florets of the ear and the gynoecium is
> represented in the florets of the tassel, even though either of these
> whorls is absent in the functional florets. The inclusion of both whorls
> in the floret ontology for the florets of ears and spikelets is based on
> this phylogenetically significant ontogeny. East and Hayes (1911, p.
> 134-135) provided the following: "Perhaps it should be mentioned in
> passing that the immature sex organs, so called, of maize seem endowed
> with the power of becoming either stamens or carpels. One often finds a
> normal ear ending in stamens, and nearly every plant produces lateral
> branches which have carpels and stamens mixed together
> indiscriminantly." Studies of mutants have explored these occurrences
> and similar occurrences in tassels, corroborating the inherent bisexual
> nature of the floret meristem prior to the subsequent development of the
> monoecious condition." (the length of this defn. possibly provides
> argument for the inclusion of some sort of comment field closely
> associated with the definition?).
>
> I've also been using the Derived/Develops_from relationship in the Zea
> ontology. This relationship accommodates the temporal & spatial needs
> associated with ontogeny e.g. the development of primordia.
>
> You'll note, when browsing the ontology via DAG-Edit, that I still need
> to provide definitions for some terms - an ever pressing need.
>
> Let me have your candid comments/thoughts.
>
> Leszek
>
> ===========================
> P. Leszek D. Vincent Ph.D., FLS
> Plant Science Unit, Dept. of Agronomy, 209 Curtis Hall,
> University of Missouri-Columbia, Columbia, MO 65211-7020, USA.
> Ph: (573) 884-3716 (Agronomy); Fax:(573) 884-7850;
> Ph/Fax (Home): (573) 441-1228;
> Email: Leszek at missouri.edu
> Yahoo! Messenger: leszekvincent
> Plant Systematist on the Plant Ontology Consortium
> Associate Curator, Dunn-Palmer Herbarium (UMO)
> Research Associate, Missouri Botanical Garden, USA
> CEO - PhytoSynergy, LLC
> =======================
>
>

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Sue Rhee                         	rhee at acoma.stanford.edu
The Arabidopsis Information Resource	URL: www.arabidopsis.org
Carnegie Institution of Washington	FAX: +1-650-325-6857
Department of Plant Biology		Tel: +1-650-325-1521 ext. 251
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