Comparison of Floral Structure and Ontogeny in Monoecious and Dioecious Species of the Palm Tribe Chamaedoreeae (Arecaceae; Arecoideae)

Abstract

Premise of research. The sexuality of flowers is an important reproductive character in angiosperms. An insight into the evolutionary events that led to the appearance of monoecious and dioecious species can be gained by comparing closely related groups with contrasting characters. For this study, we focused on the tribe Chamaedoreeae, within which dioecy appears to have evolved twice from a monoecious ancestor. Methodology. To improve our knowledge of flower structure and ontogeny in this group, SEM and anatomical sectioning were performed on inflorescences and flowers of the dioecious species Chamaedorea tepejilote and the monoecious species Hyophorbe lagenicaulis at different developmental stages. Pivotal results. Our data highlighted that the higher degree of spatial sexual separation seen in the dioecious C. tepejilote, compared to the monoecious H. lagenicaulis, is accompanied by a more accentuated dimorphism between male and female flowers. More specifically, in the case of C. tepejilote, the vestigial reproductive organs (staminodes of the female flower and pistillode of the male flower) are more rudimentary structures, in terms of their developmental differentiation, than their homologs in H. lagenicaulis. Conclusions. Our data suggest that the unisexual flowers already present in the monoecious ancestor of the Chamaedoreeae underwent further modifications either shortly before or since the appearance of dioecy in the genus Chamaedorea. These structural changes were presumably the result of genomic mutations causing earlier developmental arrest of the vestigial reproductive organs and are likely, in turn, to have conferred enhanced resource-allocation efficiency.

Morphoanatomical and histochemical studies of the seed development of Euterpe oleracea (Arecaceae)

“…The ovules in Euterpe oleracea are hemianatropous. But this is a variable condition in members of Arecaceae, which may also exhibit anatropous, campylotropous and orthotropous ovules (Uhl & Moore 1971;Genovese-Marcomini et al 2013;Mazzottini-dos-Santos et al 2015;Castaño et al 2016). Moreover, although bitegmic ovules are widely distributed in the family, the micropyle may be formed by both the integuments, as observed in E. oleracea, by the inner integument, or by the outer integument (Genovese-Marcomini et al 2013;Mazzottini-dos-Santos et al 2015) Figure 4 -a-p. Fruit and seed development of Euterpe oleracea in longitudinal sections, stages S5-S8 -a-d. stage S5 -a. developing fruit and seed (11 mm, opaque green pericarp and soft seed); b. general view of an anatomical section from the developing seed; c. young embryo showing the cotyledonary base and the upper part of the cotyledon; d. endosperm with thickened cell walls (black arrowheads) [note the primary pit fields (black arrow)]; e-h. stage S6 -e. developing fruit and seed (11 mm, opaque green pericarp and hard seed); f. general view of seed anatomy; g. detail of the embryo; h. endosperm with thickened cell walls (black arrowheads) and cytoplasmic inclusions (white arrows) [note the primary pit fields (black arrow)]; i-l. stage S7 -i. developing fruit and seed (12 mm, green-purple pericarp and hard seed); j. general view of seed anatomy with ruminate endosperm (note the development of the upper side of the cotyledon); k. detail of cotyledonal embryo; l. detail of endosperm cells with cytoplasmic inclusions, thickened cell walls (black arrowheads), and primary pit fields (black arrow); m-p. stage S8 -m. fruit and seed (12 mm, purple pericarp and hard fully developed seed); n. mature seed (note the ruminate endosperm); o. mature embryo; p. detail of endosperm with thickened cell walls (black arrowheads), primary pit fields (black arrow), and cytoplasmic inclusions (white arrows).…”

Cambios estructurales de las lipoproteínas de la pacaya por el efecto de diferentes tratamientos térmicos

“…El tepejilote cuyo nombre científico es Chamaedorea tepejilote Liebm se distribuye desde México hasta Colombia, pero se encuentran entre 45 y 50 especies en México, por lo que se considera el país con mayor diversidad de especies de este género. Oaxaca, Chiapas y Veracruz son los estados donde se concentran la mayor parte de las especies mexicanas del género, cuenta con un importante potencial bioeconómico para fines alimentarios, medicinales tradicionales y ornamentales (Castaño et al, 2016). A lo largo de su distribución en México se le conoce con varios nombres como: tepejilote, pacaya, guaya, chi ib, caña verde, ixquil, quib, chimp, bojon, aula-te, chem-chem, ternero pacaya grande y elote de monte.…”