Lygia Dolores Ribeiro de Santiago-Fernandes

Federal University of Rio de Janeiro | UFRJ · National Museum Botany Department

Most flowering plants have perfect flowers with an androecium and gynoecium that produce microgametophytes and megagametophytes, respectively. Failure in the development of the reproductive organ, functional gametophytes, or viable zygotes is known as sterility and is the main mechanism used by plants to produce unisexual flowers. When sterility is...

Reproduction in flowering plants is closely related to the megagametophyte, since the megagametophyte is involved in pollen tube reception and contains the two female gametes—egg cell and central cell. Previous conventional light microscopy methods have shown that female sterility in perfect flowers of Maytenus obtusifolia is associated with the oc...

Perfect flowers of Maytenus obtusifolia have partial sterility of pollen grains, resulting in collapsed and developed free microspores. However, the cellular events resulting in partial male sterility have not been determined. In pistillate flowers of this species, male sterility is related to the premature programmed cell death (PCD) in tapetum an...

Differences in the effectiveness of diurnal and nocturnal visitors could imply specialization in plant–pollinator interactions. Consequently, floral traits (e.g. period of anthesis onset, colours, scent, and time of nectar production) could reflect adaptation to the most effective pollinator. Despite the period of anthesis onset being frequently re...

The reproductive system of Orchidaceae is predominantly xenogamous and highly dependent on animal pollen vectors. Nectar is the main floral resource, offered to pollinators in perigonal nectaries, cuniculi or spurs; these structures are often difficult to locate and to evaluate their functionality. The Neotropical Epidendrum denticulatum Barb. Rodr...

Programmed cell death (PCD) is defined as a sequence of genetically regulated events leading to controlled and organised cellular degradation. It plays a vital role in plant development; however, little is known about the role of PCD in reproductive development. Sterility in pistillate flowers of Maytenus obtusifolia Mart. has been shown to be rela...

Maytenus obtusifolia Mart. is an abundant species in restingas (sandy coastal plains), mainly in Rio de Janeiro state, Brazil. Populations in restinga of Maricá are gynodioecious formed by female individuals with pistillate flowers and hermaphrodites with perfect flowers. Pistillate flowers bear a developed gynoecium and staminodes. Perfect flowers...

Characters of the gynoecium are considered potentially significant for the systematics of Myrtaceae. However, only two such characters – ovule number and placentation – have been addressed from an evolutionary perspective. Colleter presence in flowers is a synapomorphy of Myrtales; however, no morphological and histochemical descriptions of such st...

Galls are anomalies in plant development of parasitic origin that affect the cellular differentiation or growth and represent a remarkable plant–parasite interaction. Byrsonima sericea DC. (Malpighiaceae) is a super host of several different types of gall in both vegetative and reproductive organs. The existence of galls in reproductive organs and...

‘Gynodioecy–dioecy’ is one of the pathways by which dioecy can arise from hermaphroditism. Studies on sex determination and development of gynodioecious systems have focused on temperate and/or annual species. Little is known about the evolutionary dynamics of gynodioecy and dioecy in perennial tropical species, where these systems have more freque...

Sexual systems play a key role in the ecology and evolution of plant populations. Research on Garcinia L. has shown the occurrence of variations in the sexual systems of this genus, with some authors considering it as dioecious, and for some species as gynodioecious or androdioecious. The population of G. brasiliensis in the restinga of Marica´ is...

Garcinia brasiliensis Mart., a species from the Amazon and Atlantic rainforests, is cryptic dioecious because the morphologically perfect flowers are in fact pistillate given the absence of pollen. The flowers present diurnal anthesis, have a sweet and mild scent, and are pollinated by bees in search of the nectar secreted by evident nectaries. The...

The family Podostemaceae is exceptional among angiosperms because of its uncommon biology and morphology, the absence of double fertilisation and endosperm, and the obscure distinction between root, stem, and leaf. The highly modified morphology produced by reductions and specialisations is reflected in the multiple positions that the Podostemaceae...

Manilkara subsericea (Mart.) Dubard and Sideroxylon obtusifolium (Roem. & Schult.) T.D. Penn. display inflorescences of a fasciculate type, with perfect, nectariferous, odoriferous and hercogamous flowers. They present protogynic dichogamy and daylight anthesis. The corolla is gamopetalous, with the basal region of the lacinia forming a small tube....

Euphorbiaceae s.s. is one of the largest angiosperm families, comprising nine major lineages. Molecular analysis indicated a polyphyletic condition in the subfamily Crotonoideae s.l., with four lineages identified, including one termed inaperturate crotonoids, which encompasses the tribe Crotoneae. Anatomical data were obtained from 15 species of C...

Ageratum fastigiatum (Gardn.) R. M. King et H. Rob. (Asteraceae), known as "matapasto", is a plant used in the popular medicine as cicatrizant and antimicrobial. The aim of this work was to perform a morpho-anatomical characterization of the leaves, the stems and the roots from A. fastigiatum. Transversal and paradermic sections, stained with astra...

Somatic embryogenesis was induced from cotyledon explants of eggplant cultured on MS medium supplemented with 54 µM NAA. Anatomical analysis of somatic embryo initiation and development was performed during the first four weeks. Proembryo formation was observed after the second day of culture, directly from perivascular cells or via pro-embryogenic...

The isolation of embryogenesis-associated genes and the characterization of their roles during embryo development are important steps towards the elucidation of the molecular mechanisms controlling embryo morphogenesis. Somatic embryogenesis continues to be an effective model for studying gene expression in embryo development. We report the analysi...

Glycine-rich proteins (GRPs) are characterized by having the glycine residues arranged in characteristic repetitive structural motifs, but with distinct primary sequence. Although identified in various plant species, little is known about their contribution to the morphology and development of the organism. In this study we have isolated the atgrp-...

Abstract in English. Thesis (master's)--Universidade Federal do Rio de Janeiro, 1987. Includes bibliographical references (leaves [154]-161).