Embryogenesis in Polianthes tuberosa L var. Simple: from megasporogenesis to early embryo development

Abstract

The genus Polianthes belongs to the subfamily Agavoideae of the Asparagaceae family formerly known as Agavaceae. The genus is endemic to México and comprises about 15 species, among them is Polianthes tuberosa L. The aim of this work was to study and characterize the embryo sac and early embryo development of this species in order to generate basic knowledge for its use in taxonomy, in vitro fertilization and production of haploid plants and to complement studies already performed in other genera and species belonging to the Agavoideae sub-family. It was found that the normal development of the P. tuberosa var. Simple embryo sac follows a monosporic pattern of the Polygonum type and starts its development from the chalazal megaspore. At maturity, the embryo sac is of a pyriform shape with a chalazal haustorial tube where the antipodals are located, just below the hypostase, which connects the embryo sac with the nucellar tissue of the ovule. The central cell nucleus shows a high polarity, being located at the chalazal extreme of the embryo sac. The position of cells inside the P. tuberosa embryo sac may be useful for in depth studies about the double fertilization. Furthermore, it was possible to make a chronological description of the events that happen from fertilization and early embryo development to the initial development of the endosperm which was classified as of the helobial type.

Female gametophyte development in Sedum sediforme (Jacq.) Pau (Crassulaceae): an anatomical, cytochemical and ultrastructural analysis

“…This results in the formation of a triad composed of two chalazally placed megaspores and one binucleate cell. The triad formation has already been observed in other angiosperms (Bouman 1984; Johri et al 1992); for example, in Trifolium alexandrinum (Krupko 1973), Cytisus striatus and C. multiflorus (Rodríguez-Riaño et al 2006), Polianthes tuberosa (González-Gutiérrez and Rodríguez-Garay 2016) and also in Crassulaceae. In Crassulaceae, as in other angiosperms, the nucleus of a micropylar dyad cell can undergo meiosis II, as is in Aeonium arboreum and Rosularia sempervivum (Mauritzon 1933).…”

An F-Actin Mega-Cable Is Associated With the Migration of the Sperm Nucleus During the Fertilization of the Polarity-Inverted Central Cell of Agave inaequidens

“…Transvacuolar strands also aid in the mobility of polar nuclei, which fuse to form the central cell nucleus. In Polianthes tuberosa , another member of the Asparagaceae family, before the migration of the micropylar polar nucleus toward the chalazal end, where the other polar nucleus is located, a thin cytoplasmic strand appears traversing the central vacuole and connecting both polar nuclei ( Gonzalez-Gutierrez and Rodriguez-Garay, 2016 ). Similarly, analysis of the developmental dynamics of A. thaliana female gametophyte demonstrated that the migration of polar nuclei occurs through the middle ( Susaki et al, 2021 ) but not along the periphery of the cell ( Higaki et al, 2006 ).…”