Embryo development of Dyckia pseudococcinea (Pitcairnioideae-Bromeliaceae), an endangered Brazilian species
Simone P. Mendes A C , Cecília G. Costa B and Karen L. G. De Toni BA Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s.n., São Cristovão, Rio de Janeiro, RJ, Brasil.
B Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Diretoria de Pesquisa, Pacheco Leão 915, Jardim Botânico, CEP 22.460-030, Rio de Janeiro, RJ, Brasil.
C Corresponding author. Email: petruccimendes@gmail.com
Australian Journal of Botany 58(6) 485-492 https://doi.org/10.1071/BT10073
Submitted: 21 March 2010 Accepted: 19 July 2010 Published: 8 September 2010
Abstract
The Brazilian Atlantic Forest is a biodiversity hotspot. Many Bromeliaceae species are important components of this biome, including endemic plants, such as Dyckia pseudococcinea. However, human pressure has resulted in its designation as threatened with extinction. In an attempt to encourage the establishment of subsidised support for in vitro culture protocols that ensure its reproduction, the embryo development of this species was examined by light microscopy. Embryo development initiates with the sporophytic zygote, which undergoes a first cell division that is asymmetrical and transversal. A polarised bicellular proembryo is then formed, with an apical and a basal cell that contribute to the subsequent stages of an Asteraceae-type embryogenesis after successive divisions. Differentiation of the peripheral cells is observed during the post-octant proembryo stage that gives rise to the protoderm. At maturity, the embryo is composed of a cotyledon, shoot and root apical meristems, and a suspensor. The polarisation of the bicellular proembryo and the establishment of the protoderm were identified as the two critical stages in the embryonic development of D. pseudococcinea. Thus, in vitro propagation efforts to produce seedling plants should use proembryos from the tricellular to octant stages in view of their capacity to follow distinct morphogenetic pathways.
Acknowledgements
We thank the Graduate Program in Botany of the Museu Nacional/UFRJ; CAPES for the Masters study grant awarded to the first author; CNPq for the research grant awarded to the second author; and FAPERJ for financial support (FAPERJ 112.349/2008).
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