Endosperm development in Dyckia pseudococcinea (Pitcairnioideae - Bromeliaceae)

Abstract

Dyckia pseudococcinea is a threatened species endemic to the restingas of the Atlantic Forest, an area under strong anthropic impact. From the perspective of conservation, plant embryology is interesting by the variety of approaches for in vitro culture of seedlings. With this in mind, the present study describes the endospermogenesis of D. pseudococcinea to provide data for conservation studies and indicate characters that may contribute to the systematics of Pitcairnioideae. Using anatomical analysis, samples of flowers and fruits at different developmental stages were analyzed. We observed the establishment of the primary endosperm nucleus and then the primary endosperm cell (PEC). Upon expansion of the central vacuole of PEC, nuclei migrate to the chalazal, peripheral, and micropylar domains. An early centripetal cellularization begins in the chalazal region, characterizing the endosperm as coenocytic/multicellular type. With cellularization, the endosperm enfolds the embryo. In addition, in the outermost layer of the endosperm, an aleurone layer is visible. These observations allowed some embryological characters to be identified, thus helping to clarify the systematic relationships of Pitcairnioideae and also the genus Dyckia, such as the presence of hypostasis, the persistence of the antipodals and synergids during the early stages of endospermogenesis and coenocytic/multicellular endospermogenesis. Having established the details of endospermogenesis, we then set forth guidelines for the development of in vitro culture protocols aimed at the conservation of D. pseudococcinea, an endangered Bromeliad species of the Atlantic Forest.