Abstract
Vascular plants have evolved shoot apical meristems (SAMs), whose structures differ among plant groups. To clarify the evolutionary course of the different structural types of SAMs, we compared plasmodesmatal networks in the SAMs for 17 families and 24 species of angiosperms, gymnosperms, and pteridophytes, using transmission electron microscopy (TEM). The plasmodesmata (PD) in almost all cell walls in median longitudinal sections of SAMs were counted, and the PD density per unit area was calculated for each cell wall. Angiosperm and gymnosperm SAMs have low densities, with no difference between stratified (tunica-corpus) and unstratified structures. SAMs of ferns, including Psilotum and Equisetum, have average densities that are more than three times higher than those of seed plants. Interestingly, microphyllous lycopods have both the fern and seed-plant types of PD networks; Selaginellaceae SAMs with single apical cells have high PD densities, while SAMs of Lycopodiaceae and Isoetaceae with plural initial cells have low PD densities, equivalent to those of seed plants. In summary, PD networks are strongly correlated to SAM organizations-SAMs with single and plural initial cells have the fern and seed-plant types of PD, respectively. The two SAM organizations may have evolved separately in lycophytes and euphyllophytes and may be associated with gain or loss of the ability to form secondary PD.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 8
Claim · model-written summary
Angiosperm and gymnosperm SAMs have low plasmodesmatal densities.
Verbatim
e0“Angiosperm and gymnosperm SAMs have low densities”
Claim · model-written summary
Among angiosperm and gymnosperm SAMs, there was no difference in plasmodesmatal density between stratified (tunica-corpus) and unstratified structures.
Verbatim
e0“Angiosperm and gymnosperm SAMs have low densities, with no difference between stratified (tunica-corpus) and unstratified structures”
Claim · model-written summary
SAMs of ferns, including Psilotum and Equisetum, have average PD densities more than three times higher than those of seed plants.
Verbatim
e0“SAMs of ferns, including Psilotum and Equisetum, have average densities that are more than three times higher than those of seed plants”
Claim · model-written summary
Selaginellaceae SAMs with single apical cells have high PD densities.
- Taxon
- SelaginellaceaeSelaginellaceaee0
- Outcome
- PD densitiese0
- Direction
- highe0
Verbatim
e0“Selaginellaceae SAMs with single apical cells have high PD densities”
Claim · model-written summary
SAMs of Lycopodiaceae and Isoetaceae with plural initial cells have low PD densities, equivalent to those of seed plants.
- Taxon
- Lycopodiaceae and IsoetaceaeLycopodiaceaeIsoetaceaee0
- Outcome
- PD densitiese0
- Direction
- lowe0
- Comparator
- seed plantse0
Verbatim
e0“SAMs of Lycopodiaceae and Isoetaceae with plural initial cells have low PD densities, equivalent to those of seed plants”
Claim · model-written summary
PD networks are strongly correlated with SAM organization: SAMs with single and plural initial cells have the fern-type and seed-plant-type PD networks, respectively.
- Taxon
- vascular plantsTracheophytat0
- Organ / stage
- SAM organizationse0
- Outcome
- PD networkse0
Not reportedDirection
Verbatim
t0“vascular plants”
e0“PD networks are strongly correlated to SAM organizations”
Claim · model-written summary
The two SAM organizations may have evolved separately in lycophytes and euphyllophytes.
Verbatim
e0“The two SAM organizations may have evolved separately in lycophytes and euphyllophytes”
Claim · model-written summary
The SAM organizations may be associated with gain or loss of the ability to form secondary PD in lycophytes and euphyllophytes.
Verbatim
e0“The two SAM organizations may have evolved separately in lycophytes and euphyllophytes and may be associated with gain or loss of the ability to form secondary PD”