Diversity, distribution, development, and evolution of medullary bundles in Nyctaginaceae
Por:
Neto, Israel L. da Cunha, Pace, Marcelo R., Douglas, Norman A., Nee, Michael H., de Sa, Cyl Farney C., Moore, Michael J., Angyalossy, Veronica
Publicada:
1 may 2020
Resumen:
Premise Medullary bundles, i.e., vascular units in the pith, have
evolved multiple times in vascular plants. However, no study has ever
explored their anatomical diversity and evolution within a phylogenetic
framework. Here, we investigated the development of the primary vascular
system within Nyctaginaceae showing how medullary bundles diversified
within the family.
Methods Development of 62 species from 25 of the 31 genera of
Nyctaginaceae in stem samples was thoroughly studied with light
microscopy and micro-computed tomography. Ancestral states were
reconstructed using a maximum likelihood approach.
Results Two subtypes of eusteles were found, the regular eustele,
lacking medullary bundles, observed exclusively in representatives of
Leucastereae, and the polycyclic eustele, containing medullary bundles,
found in all the remaining taxa. Medullary bundles had the same origin
and development, but the organization was variable and independent of
phyllotaxy. Within the polycyclic eustele, medullary bundles developed
first, followed by the formation of a continuous concentric procambium,
which forms a ring of vascular bundles enclosing the initially formed
medullary bundles. The regular eustele emerged as a synapomorphy of
Leucastereae, while the medullary bundles were shown to be a
symplesiomorphy for Nyctaginaceae.
Conclusions Medullary bundles in Nyctaginaceae developed by a single
shared pathway, that involved the departure of vascular traces from
lateral organs toward the pith. These medullary bundles were encircled
by a continuous concentric procambium that also constituted the
polycyclic eustele, which was likely a symplesiomorphy for Nyctaginaceae
with one single reversion to the regular eustele.
Filiaciones:
Neto, Israel L. da Cunha:
Univ Sao Paulo, Inst Biociencias, Dept Bot, Rua Matao 277,Cidade Univ, BR-05508090 Sao Paulo, SP, Brazil
Pace, Marcelo R.:
Univ Nacl Autonoma Mexico, Inst Biol, Dept Bot, Ciudad Univ, Mexico City 70367, DF, Mexico
Douglas, Norman A.:
Univ Florida, Dept Biol, POB 1113525, Gainesville, FL 32611 USA
Nee, Michael H.:
New York Bot Garden, 2900 Southern Blvd, Bronx, NY 10458 USA
de Sa, Cyl Farney C.:
Inst Pesquisas Jardim Bot Rio de Janeiro, Rua Pacheco Leao 915, Rio De Janeiro, RJ, Brazil
Moore, Michael J.:
Oberlin Coll, Dept Biol, Oberlin, OH 44074 USA
Angyalossy, Veronica:
Univ Sao Paulo, Inst Biociencias, Dept Bot, Rua Matao 277,Cidade Univ, BR-05508090 Sao Paulo, SP, Brazil
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