Morphoanatomy and development of leaf secretory structures in Passiflora amethystina Mikan (Passifloraceae)

Abstract

Extrafloral nectaries (EFNs) are commonly found in Passiflora L. Reports have been made on the occurrence of resin-producing structures morphologically similar to EFNs in the genus. The objective of this study was to characterise the morphoanatomy and development of leaf secretory structures in Passiflora amethystina and to use chemical and histochemical tests to detect the presence of sugars in the exudates. Samples of leaf blade and petioles in different developmental stages were collected and subjected to usual techniques using light and scanning electron microscopy. Secretion samples were analysed by high performance liquid chromatography. The concentration of total sugars in the secretion amounted to 39.67% for blade EFNs and 52.82% for petiolar EFNs. EFNs consist of a secretory, uni- or bistratified palisade epidermis, arising from the protoderm by means of anticlinal and periclinal divisions, glandular parenchyma originated from the ground meristem, and xylem and phloem elements formed from the procambium. Exudate accumulated in a subcuticular space formed outside the epidermal cells from where it was then released. Histochemical tests showed a positive reaction for neutral polysaccharides. The results confirm that the leaf secretory structures are indeed extrafloral nectaries, and these findings constitute important information for studies on the taxonomy and ecology of this species.

Anatomy of the extrafloral nectaries in species of Chamaecrista section Absus subsection Baseophyllum (Leguminosae, Caesalpinioideae)

“…Their development pattern (i.e. from the protodermis and underlying layers) is in accordance with other reports on such glands found in several plant families described in the literature (Coutinho et al, 2010;Paiva et al, 2007;Rocha et al, 2009;Thadeo et al, 2008).…”

“…The presence of such substances in EFNs has also been described by other authors (Caldwell and Gerhardt, 1986;Coutinho et al, 2010;Rocha et al, 2009). On the other hand, we think that the presence of phenolic compounds in the EFNs is not necessarily an indication of its presence in the nectar.…”

Phytochemical and anti–bacterial activity of epidermal glands extract of Christella parasitica (L.) H. Lev.

“…The presence of glandular hairs or trichomes on leaf surface is of taxonomical, ecological and medicinal importance. Morphoanatomical and developmental studies on leaf secretory structures in Passiflora amethystine confirm that the leaf secretory structures are indeed extrafloral nectarines, and these findings constitute important information for studies on the taxonomy and ecology of this species [5] . Plant structures, such as trichomes, or compounds like toxins, deterrents or digestibility reducers, that directly reduce the preference or performance of an herbivore or pathogen are called direct defenses [6] .…”

Colleters in Chamaecrista (L.) Moench sect. Chamaecrista and sect. Caliciopsis (Leguminosae-Caesalpinioideae): anatomy and taxonomic implications

“…Chamaecrista and Caliciopsis are indeed colleters. Such structures are typically related to the protection of young leaves and flowers from desiccation and attack from microorganisms since the secretion present is made of mucilage or a mixture of mucilage, resin and protein (Thomas & Dave 1989;Thomas 1991;Rocha et al 2009). …”