Reciprocal intercompatibility between Byrsonima Rich. exKunth species (Malpighiaceae), in an urban ecotonal fragment of Semi-Deciduous Seasonal Forest and Cerrado

Byrsonima species present floral monomorphism and sharing visitor/pollinator guild. These traits suggest the hypothesis evaluation of reciprocal inter-incompatibility between two syntopic Byrsonima species: B. pachyphylla and B. crassifolia. Pollen tube growth with similar behavior was observed in the stigmatic surface, pistil canal, ovary and micropylar channel to both species. In addition, partial self-incompatibility in self-pollination with greater fruiting in autogamy was observed. Cross-pollination and self-pollination coexist, and reciprocal intercompatibility occurs. Prezygotic isolation mechanisms are unlikely by the absence of abnormal pollen tubes, higher fruiting production and absence of hybrids in the study site. Las especies de Byrsonima presentan monomorfismo floral y comparten gremio de visitantes/polinizadores. Estos rasgos sugieren la evaluación de hipótesis de interincompatibilidad recíproca entre dos especies sintópicas de Byrsonima: B. pachyphylla y B. crassifolia. Se observó el crecimiento del tubo polínico con comportamiento similar en la superficie estigmática, canal del pistilo, ovario y canal micropilar de ambas especies. Además, se describió la autoincompatibilidad parcial en la autopolinización con mayor fructificación en la autogamia. La polinización cruzada y la autopolinización coexisten y se produce una intercompatibilidad recíproca. Los mecanismos de aislamiento precigóticos son improbables por la ausencia de tubos polínicos anormales, producción de frutos y ausencia de híbridos en la área de estudio.

Floral Microcharacters in South American species of Senecio s.str. (Asteraceae) with considerations on the circumscription of this genus

Senecio L. s.str. is the largest genus in the tribe Senecioneae (Asteraceae) and it has been commonly characterized by its truncate, penicillate stylar tips, separated stigmatic lines, and stamens usually with ecaudate anther bases and balusterform filament collar. A micromorphological study was carried out to determine if South American species of Senecio s.str. present these diagnostic micromorphological characters, as a contribution towards a circumscription of this genus supported by morphology. The study included 72 South American Senecio species from eight sections and 16 series, as well as species from six other genera of subtribe Senecioninae (Delairea, Dendrophorbium, Dendrosenecio, Graphistylis, Lomanthus, Pentacalia), three genera of subtribe Tussilagininae (Aequatorium, Nordenstamia, Roldana), and one of subtribe Brachyglottidinae (Acrisione). The studied characters include: style branches (stigmatic surface, and apices), anthers (filament collar, bases, and appendages), as well as pollen features (shape, size, and sculpture). Analyses of these characters suggested that Senecio s.str. can be defined only by the presence of balusterform filament collars, which are present in 61 out of the 72 studied Senecio s.str. species (vs. cylindrical collar in remaining species). The genera Graphistylis and Delairea also show this trait, however, Graphistylis presents some microcharacters (e.g. “banded” stigmatic surface) that are rather infrequently found in Senecio s.str. Senecio grandis showed cylindrical collars and sagittate anther bases and should be excluded from the genus. The other microcharacters analyzed appeared to be taxonomically uninformative, since their predominant states were found in Senecio s.str. as well as in other genera of Senecioneae.

Three new species of Cypella (Iridaceae) from South America, and taxonomic delimitation of C. suffusa Ravenna

Three new species of Cypella are described and illustrated for the complex of grasslands ecosystems of Rio de La Plata: C. aurinegra, C. guttata and C. ravenniana. The former is endemic to the region of the Taquari river, southern Cerro Largo Department, Uruguay, and is closely related to Cypella fucata and C. luteogibbosa, but can be distinguished from these species by its yellow flowers stained with dark-purple, narrower outer tepals, smaller inner tepals, shorter adaxial crests of style branches, slender filaments, and seeds with smooth testa. Cypella guttata occurs in Artigas and Rivera Departments, northern Uruguay, and in Santana do Livramento Municipality, southwestern Rio Grande do Sul State, Brazil. This species resembles C. herbertii and C. lapidosa, and can be distinguished by its flowers with central depression showing red spots, filaments narrower and tape-shaped, style branches with shorter adaxial crests, and small transverse stigmatic surface of the abaxial crest. The range of geographic distribution of C. ravenniana includes southern Misiones, and northeast Corrientes Provinces, Argentina, and west and northwest Rio Grande do Sul State, Brazil. This species can be recognized by its one-flowered spathes, borne on short peduncles. Cypella ravenniana was firstly misidentified as C. suffusa; however, having as base the type and topotypical collections of the latter species, C. suffusa is recognized by its two-flowered spathes borne on long peduncles, and perigone golden-yellow with deep central concavity. Data about phenology, geographic distribution, conservation and dichotomous keys to segregate these three new species from its related species are supplied.

Ploidy analysis of Cymbidium, Phalaenopsis, Dendrobium and Paphiopedillum (Orchidaceae), and Spathiphyllum and Syngonium (Araceae)

Endopolyploidy is typical and wide-spread in the Orchidaceae. In this study, an attempt was made to quantify the ploidy of mature callus and mature protocorm-like bodies (PLBs) of nine hybrid Cymbidium cultivars cultured in vitro, as well as different flower parts (dorsal sepal, petal, lateral sepal, labellum, pedicel, column, anther cap, stigmatic surface) and youngest leaf of Phalaenopsis and Paphiopedillum and in leaf tissues of in vitro Spathiphyllum and Syngonium plants. Polyploidy was detected in in vitro cultures, primarily in PLBs, ant to a limited extent in floral tissue: 8C was detected in the pedicel and column, but never exceeding 3%. This study expands on the number and breadth of cases of endopolyploidy in orchids, with novel information about Paphiopedillum. These findings may be useful for better understanding developmental processes in vitro or in planta, and may be the first step to revealing evolutionary or adaptive mechanisms of survival of orchids in response to environmental or abiotic stresses.

Enhanced Visualization of the Fine Structure of the Stigmatic Surface of Citrus using Pre-fixation Washes

Stigma characteristics and morphology can be useful in taxonomic and phylogenetic studies, indicate relationships in stigma function and receptivity, and be valuable in evaluating pollen–stigma interactions. Problematic is that in some taxa, copious stigmatic exudate can obscure the fine structural details of the stigmatic surface. Such is the case for Citrus, which has a wet stigma type on which abundant exudate inundates surface papillae. The components of stigmatic surface compounds are highly heterogeneous and include carbohydrates, proteins, lipids, glycoproteins, and phenolic compounds. This study evaluated the efficacy of several pre-fixation wash treatments on removing surface exudate to visualize the underlying stigmatic surface. Wash treatments included various buffer solutions, surfactants, dilute acids/bases, and solvents. Stigmas prepared using conventional fixation methods in glutaraldehyde had considerable accumulations of reticulate surface deposits with stigmatic cells obscured. Pre-fixation washes containing solvents such as methanol, chloroform, and ethanol left accumulations of incompletely removed exudate and crystalline deposits. Alkaline water washes produced a crust-like deposit on stigma surfaces. Buffer washes left residues of plaque-like deposits with perforated areas. In contrast, excellent removal of stigmatic exudate was obtained with a pre-fixation wash composed of 0.2 M Tris buffer, pH 7.2, containing 0.2% Triton X-100 surfactant and allowed clear imaging of the stigma and surface papillae morphology. A central sinus and radially arranged openings on the stigmatic surface were clearly visible and shown for the first time using scanning electron microscopy (SEM).

The formation of the stigmatic surface in Passiflora elegans (Passifloraceae)

The stigma surface is a complex multicellular structure where the development of the pollen tube begins. This development is necessary for sucess in fertilization and depends on recognition processes that involve the anatomy of the stigma. Passiflora is an economically important genus because of its edible fruits. Many authors have described the stigma of Passiflora but nothing is known about the ontogenesis of this structure. This work aimed to describe the formation of the stigmatic surface of Passiflora elegans. Results showed that, in bud, the stigmatic surface of this species is flat with small cells. The cells in the subdermal layer have large vacuoles and the nucleus, near to the external periclinal walls. During its development the stigma surface becomes uneven due to the elongation of cells in the subdermal layer. Elongation results in an increase of external secretory surface area of the stigmas, and probably plays an important role in pollen recognition. The polysaccharide content found in the inner walls of these structures might be involved in the signal process for pollen tube growth during its early development. The morphological evidence presented here shows that, as the stigma of Passiflora is formed by dermal and subdermal cells, it should not be characterized as colleters or papillae and, therefore, it is defined here as stigma emergences.

Stigmatic surface in the Vochysiaceae: reproductive and taxonomic implications

The Vochysiaceae are Neotropical trees and shrubs, common in the savanna areas in Central Brazil (Cerrados). The family has been traditionally divided into two tribes: Erismeae, with three genera, and Vochysieae, with five genera. We investigated the stigmatic surface of six Vochysiaceae species, belonging to four genera of Vochysieae: Vochysia, Salvertia, Callisthene and Qualea. Flowers and buds at different developmental stages were collected. Morphological features were observed on fresh material and stigmatic receptivity was inferred based on esterasic activity. Pistils were fixed and embedded in paraplast and sectioned on a rotary microtome; the sections were stained before histological analysis. Stigmas of open flowers were also observed by scanning electron microscopy. Stigmas of all species were wet and showed esterasic activity at pre-anthesis and anthesis stages. Stigmatic surface was continuous with transmitting tissue of glandular nature. Vochysia and Salvertia stigmatic surfaces were formed by multicelular uniseriate hairs, and species of the remaining genera showed papillate surface. The exudate over mature stigmas in all species flowed without rupture of stigmatic surface and pollen tubes grew down between hairs or papillae. Differences on the stigmatic surface agreed with a phylogenetic reconstruction that separated two clades and indicated that Vochysieae is not monophyletic. Stigmatic features could not be associated with pollination and breeding systems.