Anatomy and fruit development in Schinopsis balansae (Anacardiaceae).

Anales del Jardín Botánico de Madrid, 2010

2016

– The endocarp has taxonomic importance in Anacardiaceae and the study of its development is essential in order to identify its structure and whether it belongs to the Anacardium-type or Spondias-type. The placentation region is the ideal location for endocarp analysis. The fruits of Schinus terebinthifolius Raddi are drupes and the endocarp originates exclusively from the epidermis of the locular cavity. The periclinal divisions, responsible for endocarp formation, begin at anthesis, and fi nish within 72 hours. During this phase, the innermost cells of the ovarian mesophyll and the cells of the locular epidermis have similar structures. The endocarp develops in three organized layers of sclereids, making it the Anacardium-type. This endocarp differs from those previously described with four cell layers that include the crystalliferous layer, revealing a different pattern of development. Key words: Anacardiaceae, crystal layer, development, endocarp, Schinus RESUMO – Desenvolviment...

Premise of research. Most studies of Anacardiaceae embryology have focused on seed and fruit development in different genera. None of them, however, included species of Schinopsis. Considering the absence of embryo-logical data and the precedents of chalazogamy in the Anacardiaceae family, the aims of this study were to complete the embryological studies in Schinopsis balansae, providing information about micro-and megasporogen-esis and gametogenesis, fertilization, and embryogenesis, and to investigate the development of the gynoecium and the pathway of the pollen tube. Methodology. Flowers and fruits of S. balansae, a dioecious tree from the family Anacardiaceae, were collected and fixed in the field. The embryology was examined using fluorescence microscopy, LM, and SEM. Mi-crotome section series were used to reconstruct the structure and pollen tube pathway. Pivotal results. Staminate flowers have only rudimentary gynoecia, and the anthers are bithecal and tetra-sporangiate. The tapetum is secretory and uninucleate, and the pollen grains are bicellular. The morphologically bisexual flowers are functionally pistillate, and staminodia without sporogenous tissue or pollen grains are present. The pistillate flowers have a superior tricarpellate ovary with three styles, each ending in a capitate stigma. The gynoecium is pseudomonomerous, possessing one fertile carpel (with one locule and a single anatropous, crassinucellar, and unitegmic ovule) and two aborted lateral carpels that neither produce an ovule nor form a locule. Embryo sac development conformed to the Polygonum type. Bicellular pollen grains germinate on the stigma and penetrate the transmitting tract inside the styles. At the apical portion of the ovary, pollen tubes grow through the carpel wall and reach the dorsal portion of the bent funicle, which is in close contact and forms a functional ponticulus. Inside the funicle, the pollen tubes continue through the vascular bundle, where they are branched. One branch continues inside the vascular bundle to the chalaza. Fertilization was aporogamous: the pollen tubes encircled the embryo sac, reaching one synergid. Embryos follow the Onagrad type. The endo-sperm development is of the coenocytic/multicellular type. Conclusions. The structural floral features described here are shared by other species of Anacardiaceae. The results of the embryological studies in S. balansae provide information about micro-and megasporogenesis and gametogenesis, fertilization, and embryogenesis and describe for the first time the developments of the gynoecium and the unique pollen tube pathway and fertilization; the term funiculogamy was proposed to define this type of pollen tube penetration.

Pollen wall development of Illicium floridanum and Schisandra chinensis have been studied and compared. Both species have a similar reticulate exine, but their similarity occured to be only superficial. At early tetrad stage of both species the plasma membrane acquires a regularly invaginative profile, the distribution pattern of invaginations on the microspore surface corresponds to the future reticulate exine pattern. In the invaginative sites of the plasma membrane of both species fibrillar strands appear which are the auxiliary (phantom) structures. Further developmental process is different in both species. In Illicium sporopollenin accumulates around the auxiliary strands, localized in plasma membrane invaginations, resulting in the appearance of the reticulate sculpture of hollow tunnels on the surface of a microspore; this reticulate pattern becomes concave after lifting of the invaginated portions of the plasma membrane. In Schisandra, on the contrary, sporopollenin never accumulates in the location of the auxiliary fibrillar strands (these are sites of future lumina), but sporopollenin accumulations concentrate on the elements of the glycocalyx on the evaginated top (protruding sites) of plasma membrane. The latter are sites for columellae formation, and muri are constructed from the rows of columallae covered by tectum. Hence, the development of the exine in both species is different, and the inner structure of reticulate exine in Illicium differs from that of Schisandra-in spite of the very similar sculpture.

Botanical Journal of the Linnean Society, 2012

Botanical Journal of the Linnean Society, 2011

Brazilian Journal of Botany, 2014

The South American species of the genus Viguiera (Asteraceae) have been transferred to Aldama based on molecular studies. However, the circumscription of Aldama tenuifolia and A. kunthiana has not been well established because the two species are morphologically similar. Both occur in areas of the Cerrado domain, especially in ‘‘campos sujos’’, ‘‘campos limpos’’ and ‘‘campos rupestres’’, which are characterised by intense solar irradiation, water scarcity during the autumn and winter, and frequent fires. The aim of the present study is to analyse the anatomy of the vegetative organs of both species in order to identify features that may be useful in their circumscription and in understanding their environmental adaptations. Samples of leaves, stems, xylopodia and roots of each species were collected, fixed, and processed according to the usual methods for light and scanning electron microscopy. The anatomical features useful to delimit the two species are the contours of the epidermal cell walls and in the occurrence of secretory ducts in the primary phloem and fundamental parenchyma of the midrib (leaves), the occurrence of secretory ducts in the primary and secondary phloem (stems) and the degree of cambial activity in the tuberisation process (roots). Regarding the environmental adaptation, both species share the presence of a xylopodium with a high bud shoot-forming potential, fructan accumulation in the tuberised roots, root-mycorrhizal associations, the occurrence of secretory structures, such as glandular trichomes (stems and leaves), internal secretory spaces (roots, xylopodia, stems and leaves) and hydathodes (leaves).

Acta Scientiarum. Biological Sciences, 2014

Annals of Botany

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