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

Abstract

BackgroundThe 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.ResultsThe 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.ConclusionsThe 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-014-0074-2) contains supplementary material, which is available to authorized users.

Extrafloral nectaries in Leguminosae: phylogenetic distribution, morphological diversity and evolution

“…15F; Cochliasanthus caracalla, Fig. 15 G) and these lateral inflorescences with highly compressed axes (Ojeda et al 2014) are commonly referred to as pseudoraceme nodes (e.g. Delgado-Salinas et al 2011).…”

Morpho–anatomical and ultrastructural analysis of extrafloral nectaries in Inga edulis (Vell.) Mart. (Leguminosae)

“…In addition to ecological studies, aspects of EFN structure and secretion dynamics, as well as release, have drawn the attention of many researchers seeking to understand the secretory process (Mačukanović-Jocić et al 2007, Vassilyev 2010, Stpiczyńska et al 2011. The investigation of morphological and anatomical characteristics can provide subsidies to taxonomic studies (Coutinho et al 2012, Aguirre et al 2013, Ojeda et al 2014, as well as contribute to understanding the mechanisms of nectar production and release (Mačukanović-Jocić et al 2007, Heil 2016, Rodríguez-Morales et al 2016, Delgado et al 2017.…”

“…The secretion by EFNs is closely associated with the ultrastructural characteristics of their cells. Secretory cells of Leguminosae EFNs presents dense cytoplasm, small vacuoles, a considerable number of mitochondria and well developed endoplasmic reticulum, as well as highly active Golgi complexes (Davis and Gunning 1992, Horner et al 2003, Paiva and Machado 2006, Paiva 2009, Ojeda et al 2014. Nectar secretion can occur through different routes, including modified stomata, trichomes, pores, ruptures or permeable regions of the cuticle, or through cell degradation (Paiva and Machado 2006, Melo et al 2010, Silva et al 2017.…”

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

“…Ontogenetic studies involving floral development in Leguminosae are abundant (Tucker 1984, Tucker 2003, Gonçalves Leite et al 2015, especially in some Mimosoideae (Ramirez-Domenéch & Tucker 1988), in several Caesalpinieae (Kantz & Tucker 1994) and in some Papilionoideae (Tucker 1989, Tucker & Stirton 1991, Gonçalves Leite et al 2015. The EFNs in papilionoid inflorescences studied so far originate due to flower bud abortion (Ojehomon 1968, Tucker 1987, 2003, Ojeda et al 2014. Tucker (1987) mentioned the presence of rudimentary flowers in the expanded secondary axis of the inflorescences of Vigna radiata, referring that they do not develop into flowers, but in nectaries, though the development process was not described.…”

“…EFNs development in Vigna was studied in Vigna unguiculata (L.) G. W. Walpers (Ojehomon 1968, Ahmed et al 1992, 1993, Vigna adenantha (G.F.W. Meyer) Marèchal, Mascherpa & Stainier (Ojeda et al 2014), Vigna candida and V. caracalla (Ojeda et al 2015).…”