The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like "Cerrado" vegetation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Correlated matings in dioecious tropical tree, Myracrodruon urundeuva fr. all.

The correlated matings in two populations (Selvíria - SEL and Paulo de Faria - PFA) of dioecious Myracrodruon urundeuva were studied in the Southwest of Brazil, by allozyme analysis of progeny arrays using the sibling-pair model. Open-pollinated seeds were collected from 25 to 30 trees within populations. Departure from random matings were evident from the differences in pollen and ovule allele frequencies. The high and significant correlation of paternity (SEL r̂p = 0.671 ± 0.074; PFA r̂p = 0.371 ± 0.062) and a low number of effective pollinating trees (ranging from 2 to 3) were detected in the populations, suggesting high proportion of full-sibs progenies. According to these results, the estimate of coancestry within families (θ = 0.209 - SEL; θ = 0.171 - PFA.) exceeded the expectation of the half-sib progenies (θ = 0.125). Result outcomes are discussed from a conservation and breeding point of view.

Comparative embryology and taxonomic considerations in Eriocaulaceae (Poales)

The genus concept within Eriocaulaceae is widely discussed because it is mainly based on a small number of floral characteristics of unknown functional and evolutionary significance. The aim of the present work is to comparatively study the embryology of representatives of most genera of Eriocaulaceae to identify relevant features that might aid in circumscribing them. In Eriocaulaceae, the uniformity of the embryological characteristics makes it difficult to interpret the existing relationships among the genera. Some embryological characteristics, especially those related to the number of microsporangia, are shown to be unstable and restricted to Paepalanthoideae. The unique pollen morphology may be related to mechanical processes to accommodate the increase in volume after early formation of the pollen wall and may indicate a relationship to an inaperturate ancestor. The placentation, formerly stated to be axile, is more likely to be central due to protusions of the locular base. The shape of the proximal region of the megagametophyte may be responsible for the formation of the antipodal cyst. The seed coat structure is uniform in origin and is a consistent taxonomic characteristic of the family. A review of Eriocaulaceae is necessary, in which additional morphological and anatomical characteristics should be considered and combined. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Homologies of the flower and inflorescence in the early-divergent grass anomochloa (poaceae)

Premise of the study: The grass subfamily Anomochlooideae is phylogenetically significant as the sister group to all other grasses. Thus, comparison of their structure with that of other grasses could provide clues to the evolutionary origin of these characters. Methods: We describe the structure, embryology, and development of the flower and partial inflorescence of the monotypic Brazilian grass Anomochloa marantoidea. We compare these features with those of other early-divergent grasses such as Pharus and Streptochaeta and closely related Poales such as Ecdeiocolea. Key results: Anomochloa possesses several features that are characteristic of Poaceae, notably a scutellum, a solid style, reduced stamen number, and an ovary with a single ovule that develops into a single indehiscent fruit. Interpretation of floral patterning in Anomochloa is problematic because the ramification pattern of the florets places the bracts and axes in unusual positions relative to the primary inflorescence axis. Our study indicates that there is a single abaxial carpel in Anomochloa, probably due to a cryptic type of pseudomonomery in Anomochloa that resembles the pseudomonomery of other grasses. On the other hand, the Anomochloa flower differs from the typical grass flower in lacking lodicules and possessing four stamens, in contrast with the tristaminate condition that characterizes many other grasses. Conclusions: Using the median part of the innermost bract as a locator, we tentatively homologize the inner bract of the Anomochloa partial inflorescence with the palea of other grasses. In this interpretation, the pattern of monosymmetry due to stamen suppression differs from that of Ecdeiocolea. © 2012 Botanical Society of America.

Evaluation of the floral vasculature of the Janusia, Mascagnia and Tetrapterys species as a tool to explain the decrease of floral organs in Malpighiaceae

The family Malpighiaceae is considered monophyletic, but the intra-family classification is conflicting. Analyses of floral vasculature allow the identification of reductions, connations and adnations and can even reveal evolutionary steps prior to current floral morphology. The present work analysed the floral vasculature of Janusia mediterranea, Mascagnia cordifolia and Tetrapterys chamaecerasifolia using material processed by traditional methods for light microscopy. A general pattern was observed of three bundle traces supplying each sepal and one trace per petal and stamen; Mascagnia is an exception, as its eglandular sepal has only a median trace but shares lateral traces with adjacent sepals. No dorsal traces are emitted to the carpels; however, three intercarpellary complexes are emitted that divide into six ventral bundles, supplying the ovule. Mascagnia demonstrates connation between the anterior and adjacent sepal glands; reductions of the anterior sepal glands were registered in Tetrapterys and Janusia. This work reveals two distinct processes for gland loss in non-related groups of the family that resulted in similar present appearances. Our evaluation of the number of calyx glands and the processes of glandular loss in species with less than ten glands improves our understanding of the evolution of calyx glands in Malpighiaceae. © 2013 Elsevier GmbH.

Sporophytic apomixis in polyploid Anemopaegma species (Bignoniaceae) from central Brazil

Apomixis and polyploidy have been important in the evolution of the angiosperms, and sporophytic apomixis has been associated with polyembryony and polyploidy in tropical floras. We studied the occurrence of polyembryony in populations of tetraploid Anemopaegma acutifolium, A.arvense and A.glaucum from the Brazilian cerrados, and histological features of sexual and apomictic processes were investigated in A.acutifolium. All populations and species were polyembryonic (68.9-98.4% of seeds). Normal double fertilization occurred in most ovules, with exceptions being that 3% of ovules were penetrated but not fertilized and in 4% of ovules both synergids were penetrated. The penetration of both synergids suggests a continuous attraction of pollen tubes and polyspermy. Adventitious embryo precursor cells (AEPs) arose from nucellar and integumental cells of the ovule in pollinated and unpollinated A.acutifolium, indicating sporophytic apomixis. However, further embryo and endosperm development required pollination and fertilization. This pseudogamy also allows concurrent sexual embryo development. Similar polyembryony rates and polyploidy indicated that A.arvense and A.glaucum are also apomictic, forming an agamic complex similar to that observed for some species of confamilial, but not closely related Handroanthus. The co-occurrence of apomixis and polyploidy in different groups of Bignoniaceae indicates homoplasious origin of these agamic complexes. © 2013 The Linnean Society of London.

Mating in the pseudogamic apomictic Anemopaegma acutifolium DC: Another case of pseudo-self-compatibility in Bignoniaceae?

Self-compatibility in apomictic pseudogamic species is considered fundamental to assure reproduction by seeds in extreme situations, making apomictic species more advantageous than sexual ones in these scenarios. Anemopaegma acutifolium is a polyploidy, apomictic sporophytic species with no endosperm development in ovules of unpollinated pistils, which indicates obligate pseudogamy. Thus, the aim of the present work is to study the breeding system and post-pollination events to test if there is similar pseudogamous development irrespective of pollination treatment. We analysed fruit and seed set obtained in controlled experimental pollinations, as well as embryo number per seed, and the progress of ovule penetration, fertilisation and early endosperm development between self- and cross-pollinated pistils. We found that the species is self-fertile and that spontaneous selfing fruit set is also possible, although emasculated flowers never form fruits. Selfed pistils were as efficient as crossed ones for all parameters analysed, except for a delay in endosperm development observed in the former that may be an effect of the late-acting self-incompatibility. Therefore, the avoidance of selfed pistil abortion seems to be promoted by the presence of adventitious embryos and a normal endosperm. We conclude that A. acutifolium shows apomixis-related pseudo-self-compatibility, as in other self-fertile apomictic species of Bignoniaceae, which confer reproductive assurance and increases fruit-set and persistence ability in fast-changing tropical habitats. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Estudos taxonômicos e anatômicos em Mayacaceae kunth

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ontogenia e anatomia do gineceu de espécies de Anthurium Schott (Araceae, Alismatales)

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Morfoanatomia dos órgãos reprodutivos e da plântula de Epiphyllum phyllanthus (L.) Haw. (Cactaceae)

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Ontogenia do óvulo e da Antera de Cybistax antisyphilitica (Mart.) Mart. (Bignoniaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morfoanatomia do fruto, semente e plântulas de Acalypha gracilis (Spreng.) Müll. Arg., Euphorbia cotinifolia L. e Jatropha gossypiifolia L. (Euphorbiaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Embriologia e desenvolvimento de frutos e sementes de Eriocaulaceae e Cyperaceae (Poales)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Embriologia e desenvolvimento pós-seminal de espécies de Poaceae (Poales)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morfoanatomia do pericarpo, semente, folha de Psychotria hoffmannseggiana (Willd. ex Roem. & Schult.) Müll. Arg. e Psychotria trichophora Müll. Arg., e desenvolvimento morfológico da plântula de Psychotria hoffmannseggiana (Willd. ex Roem. & Schult.) Müll. Arg. (Rubiaceae, Rubioideae, Psychotrieae)

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC