Embryology of the wild fruit tree Sideroxylon obtusifolium (Sapotaceae)

Abstract

Sideroxylon obtusifolium (Humb. ex Roem. & Schult.) T.D. Penn. is a tree species belonging to the Sapotaceae family, whose black berries can be consumed fresh or as jam. It is widely distributed in Mexico, Belize, Costa Rica, Venezuela, Bolivia, Brazil, Paraguay, Argentina, and Uruguay. While previous studies have focused on describing its floral biology, the development of the ovule and pollen has not been studied from an anatomical point of view. To provide further insights into the sexuality of this fruit tree, we conducted a study of the processes of sporogenesis and gametogenesis using conventional plant anatomical techniques. Flowers of different sizes were fixed in FAA, embedded in paraffin, sectioned, and stained with Safranin-Astra Blue for light microscopy. The processes of sporogenesis and gametogenesis result, on the one hand, in the anatropous, unitegmic, and tenuinucellate ovule, with a Polygonum embryo sac. On the other hand, it gives pollen grains that are released as monads in a tricellular state. This study provides anatomical data not previously described for this species and is part of the embryological studies that are currently being carried out in different species of fruit trees in South America. These findings enhance the embryological understanding of Sapotaceae and offer a foundation for future research in systematics, phylogeny, and conservation biology of Sapotaceae.