Variability in the indument of Phaseolus vulgaris var. aborigeous (Fabaceae)

The indument of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet, a native bean from Argentina, potential source for improvement of cultivated varieties, was compared between different genetic lines. Seeds collected from wild, weedy forms and presumptive hybrid individuals in two distant latitudes were sown in two sites of Buenos Aires University Campus (field and greenhouse). Two type of trichomes were found, which differenciate in length and shape. The pubescence density was significantly different between wild specimens from different latitudes and between culture sites for plants of a same procedence. This character could be involved in physical defences of these plants.Fil: Ojeda, Fabiana Soledad. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Plan. Toxicas y Medic., Metab. de Comp. Sinteticos y Nat.- Hongos que Intervienenen la Deg.; Argentina;Fil: Amela Garcia, Maria Teresa. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Plan. Toxicas y Medic., Metab. de Comp. Sinteticos y Nat.- Hongos que Intervienenen la Deg.; Argentina;Fil: Hoc, Patricia Susana. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Plan. Toxicas y Medic., Metab. de Comp. Sinteticos y Nat.- Hongos que Intervienenen la Deg.; Argentina

Development and differentiation of the extrafloral nectaries from flower buds in Vigna luteola (Leguminosae, Phaseolinae)

To study the ontogeny of the extrafloral nectaries present in the inflorescences of Vigna luteola (Jacq.) Benth (Leguminosae, Phaseolinae), the location, morphology, anatomy of the earliest stages, histology of the definitive structures and ultrastructure of the secretory stage were analyzed. The extrafloral nectaries at different developmental stages were examined with light microscopy and scanning electron microscopy. The secretory stage was also examined with transmission electron microscopy. The racemose inflorescence of V. luteola has six nodes. At each node, a short globose secondary axis bears two flowers and one to three extrafloral nectaries. Each extrafloral nectary originates from the abscission of a flower bud and is formed by two differentiated zones: a ring of epidermal cells surrounding a group of longitudinally enlarged papillose central cells, both with underlying secretory parenchyma. The primary secretory tissue consists of the central cells, while the ring contributes to secretion to a lesser degree. Secretion is granulocrine, by means of exocytotic vesicles and plasmalemma invaginations. Four developmental stages succeed; the third one being the secretory. The extrafloral nectaries activity period starts when the flowers of the same secondary axis open and ceases before fruit development.Fil: Ojeda, Fabiana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Galati, Beatriz Gloria. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Amela Garcia, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

Origin and ontogeny of the extrafloral nectaries associated to the inflorescences of Vigna candida and Vigna caracalla (Leguminosae, Phaseoleae)

The morphology , ontogeny and secretion of the extrafloral nectaries (EFNs) in the inflorescences of Vigna candida and Vigna caracalla were studied. The node s along the inflorescences were processed with standard techniques for light as well as scanning and transmission electron microscopy. In each node, several EFNs are formed between the flowers. The EFNs originate from flower buds that stop their growth and detach, leaving an orifice bellow which there are longitudinally enlarged cells (central cells) surrounded by a circular mound (ring). Both zones secrete. Fo u r ontogenetic stages succeed , being the third the secretory one. In each node, different EFNs are in different stages of development simultaneously , so there is always a functional nectary accompanying the flowers buds, the flowers in anthesis or the maturing fruits. Ultrastructure characteristics suggest that secretion follows the granulocrine pathwa y. The two studied species, together with Vigna adenantha, which belong to the same subgenus, share the most important characters, but differ from the corresponding ones of V igna luteola, w h ich is placed in a different subgenus, so the EFN traits support t he current classification. This is the first report about taxonomic implications of the EFNs of New World species of Vigna.Fil: Ojeda, Fabiana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Hoc, Patricia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Galati, Beatriz Gloria. Universidad de Buenos Aires. Facultad de Agronomia. Cátedra de Botanica General; ArgentinaFil: Amela Garcia, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

Ontogeny of the extrafloral nectaries of Vigna adenantha (Leguminosae, Phaseolae) and its relation with floral development

Background: The inflorescences of the genus Vigna Savi have extrafloral nectaries (EFNs) among the flowers whose origin is still unknown. The disposition, anatomy and morphology, as well as the ontogeny of the extrafloral nectaries (EFNs) associated with the inflorescences of Vigna adenantha (G.F.W. Meyer) Maréchal, Mascherpa & Stainier (Leguminosae, Papilionoideae, Phaseolae) were studied. Besides, the ultrastructure of the secretory stage was described. Results: The inflorescence, a raceme, bears a brief globose secondary axis in each node with 2 flowers and 5–7 EFNs, which develop in acropetal direction. Each EFN originates from the abscission of a flower bud that interrupts its development, resulting in an elevated EFN. This secretory structure is formed by a ring of epidermal and parenchymatic cells surrounding a group of elongated central cells. The nectary is irrigated by phloem and xylem. Four developmental stages proceed; each one relates to a different embryological stage of the flowers in each secondary axis. Conclusions: The first functional EFN of each secondary axis of the inflorescence reaches its maturity when both the pollen grains and the embryo sacs are completely developed and the flowers begin to open. The secretion is granulocrine. The following EFNs develop in the same way. Keywords: Extrafloral nectaries Inflorescences Ontogeny Morphology Anatomy Ultrastructure Vigna LeguminosaeFil: Ojeda, Fabiana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Hoc, Patricia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Galati, Beatriz Gloria. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General; ArgentinaFil: Amela Garcia, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

Extrafloral nectaries of species of Vigna from Argentina : morphology, origin, function

Se estudió la biología reproductiva de cuatro especies de Vigna nativas de la Argentina con potencial forrajero y/u ornamental. Vigna adenantha (G. F. W. Meyer) Maréchal Mascherpa & Stainier, Vigna candida (Vell.) Maréchal Mascherpa & Stainier, Vigna caracalla (L.) Verdc. y Vigna luteola (Jacq.) Benth., en poblaciones naturales y en un cultivo en C.A.B.A. Se investigó la ontogenia, morfología y función de los nectarios extraflorales (NEFs) asociados a las inflorescencias, así como la utilidad de éstos para la taxonomía. Además se exploraron otros aspectos reproductivos relacionados con los NEFs plausibles de contribuir a esta disciplina: morfología de semillas y plántulas, longevidad de las plantas, biología floral y sistema reproductivo. Los caracteres que resultaron útiles fueron la morfología de las semillas y de las plántulas, el tipo de germinación, la longevidad de las plantas, los atributos florales, la cantidad de NEFs, su anatomía y citología. Los NEFs se originan de flores abortivas. La secreción e granulocrina. La ontogenia del primer o único NEF funcional es concordante con el desarrollo del polen y del megagametofito de las flores del mismo nudo. Las hormigas que visitaron los NEFs no constituyeron una defensa biológica contra los fitófagos, tratándose de un mutualismo laxo.The reproductive biology of four species of Vigna native from Argentina with potential value as forage or ornamental crops, Vigna adenantha (G. F. W. Meyer) Maréchal Mascherpa & Stainier, Vigna candida (Vell.) Maréchal Mascherpa & Stainier, Vigna caracalla (L.) Verdc. and Vigna luteola (Jacq.) Benth., was studied in natural populations and in a culture in C.A.B.A. The ontogeny, morphology and function of the extrafloral nectaries (EFNs) associated with the inflorescences were investigated, as well as the utility of these for taxonomy. Additionally, other reproductive features related with the EFNs that could contribute to that discipline were studied: the morphology of the seeds and seedlings, plant longevity, floral biology and reproductive system. The useful characters were the seed and seedling morphology, germination type, plant longevity, the floral atributes, quantity of EFNs, their anatomy and citology. The EFNs develop from abortive flowers. The secretion is granulocrine. The ontogeny of the first or single EFN coincides with the pollen and megagametophyte development of the flowers in the same node. The ants that visited the EFNs did not constitute a biological defense against phytophages, so this relationship must be interpreted as a lax mutualism.Fil:Ojeda, Fabiana Soledad. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Two Vigna Species Native to Argentina with Ornamental Potential

Vigna candida (Vell.) Maréchal, Mascherpa and Stainier and V. adenantha (G.F.W. Meyer) Maréchal, Mascherpa and Stainier have potential as ornamentals and could be used as forage crops in warm areas. They are scandent, stolonate and pluri-annual. In both species the flowering period begins in springtime and last until autumn. The flowers are flag blossoms, disposed in 5-10-flowered racemes of 10 cm long. The standard and the keel are white, the wings are white with violet nectar guides; a variation in the color pattern of these petals occur between the species. During the anthesis, that lasts 1-2 days, an anular nectary that surround the ovary secrete the nectar offered as reward. Legitimate flower visitors are species of Xylocopa, Centris and Bombus (Hymenoptera), because of only these individuals can trigger the system of pollen transfer; also, nectar and pollen thieves or robbers were detected but did not affect the reproductive success. In V. candida, aroma is also emitted as other secondary attractant. Experiments of controlled pollinations were carried out in order to know the reproductive system of each species. V. adenantha is self-compatible but the reproductive success reach the 100% when pollinators visit the flowers, oppositely, in V. candida, which is self-incompatible, if pollinators do not work, fruits and seeds cannot be produced. Because of the growing pattern, phenology, the beautiful and conspicuous flowers, and the nitrifying capacity, both species should be appreciated as ornamentals in warm or temperate areas, even in flooded land.Fil: Hoc, Patricia Susana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Est.de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Ojeda, Fabiana Soledad. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio del Grupo de Est.de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin

Morphology of seeds and seedlings of four species of Vigna Savi (Leguminosae, Phaseolinae)

Four neotropical species of Vigna Savi (Leguminosae, Phaseolinae) have potential value as forage crops or ornamentals and could be cultivated in tropical or subtropical areas, even on floodplains. In order to obtain useful data for their culture and taxonomy, the seed morphology, germination pattern (hypogeal or epigeal) and seedling development were studied. The studied species belong to different sections of the genus: V. adenantha (G.F.W. Meyer) Maréchal, Mascherpa & Stainier (Sect. Leptospron); V. candida (Vell.) Maréchal, Mascherpa & Stainier (Sect. Sigmoidotropis); V. caracalla (L.) Verdc. (Sect. Caracallae) and V. luteola (Jacq.) Benth. (Sect. Vigna). The seeds were collected during fieldwork conducted in northwestern and northeastern Argentina. The qualitative and quantitative characters of the seeds were registered, after which they were sown. The development of the emerged seedlings was followed, first in a greenhouse and thereafter in open field. We recorded the type of germination, the thigmotropic movements of the hypocotyl and of the stem, seedling architecture and plant longevity. These traits allowed us to differentiate the species and construct an identification key that could be useful for agronomic or floricultural purposes. The data obtained partially support the current taxonomic treatment of the genus.Fil: Ojeda, Fabiana Soledad. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina;Fil: Hoc, Patricia Susana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina;Fil: Amela Garcia, Maria Teresa. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental; Argentina