Anatomical and histochemical characterization of extrafloral nectaries of Prockia crucis (Salicaceae)

Abstract

Besides being vital tools in taxonomic evaluation, the anatomy of plant secretory structures and the chemical composition of their secretions may contribute to a more thorough understanding of the roles and functions of these secretory structures. Here we used standard techniques for plant anatomy and histochemistry to examine secretory structures on leaves at different stages of development of Prockia crucis, to evaluate the origin and development of the structures, and to identify the disaccharides and monosaccharides in the exudates. Fructose, glucose, and sucrose constituted up to 49.6% of the entire secretion. The glands were confirmed to be extrafloral nectaries (EFNs); this is the first report of their presence in the genus Prockia. These EFNs are globular, sessile glands, with a central concavity occurring on the basal and marginal regions of the leaf. The epidermis surrounding the concavity is secretory, forming a single-layered palisade that strongly reacts with periodic acid-Schiff's reagent (PAS) and xylidine Ponceau, indicators of total polysaccharides and total proteins, respectively, in the exudate. On the basis of the similarity of these glands to the salicoid teeth in Populus and Salix, we suggest that these three taxa are phylogenetically close.

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).…”

“…As reported by several authors, the accumulation of secretion below a lifted cuticle (which later ruptures) is a general feature for EFNs (McDade and Turner, 1997;Nepi, 2007;Thadeo et al, 2008). However, as cuticular ruptures or detachments were not observed, we do not think that this is the case for the species studied here.…”

Comparative anatomy of calyx and foliar glands of Banisteriopsis C. B. Rob. (Malpighiaceae)

“…However, these authors opted to call such glands extrafloral nectaries (EFN) based on ultrastructural analyses and detection of sugar in the secretion. Anatomically comparable secretory structures have been described for Hymenaea stigonocarpa (Paiva & Machado 2006), Passiflora foetida (Durkee et al 1984) and Prockia crucis (Thadeo et al 2008), which produce different compounds. In such cases it is necessary to clarify the nature of the secretion.…”

The obscure events contributing to the evolution of an incipient sex chromosome in Populus: a retrospective working hypothesis

“…These compounds are thought to protect the flowers from lethal and semilethal attacks from microorganisms (Theis et al 2009;Thadeo et al 2008;Vamosi and Otto 2002). Moreover, many of these compounds vary between tissue types, flower structures, gynomorphs, and andromorphs (Kaltz and Shykoff 2001;Strauss 1997;Carlson et al 1948).…”

“…Populus and other members of the Salicaceae family are known to produce antimicrobial and antifungal compounds in nectary found near meristematic tissues, and that these compounds contribute to plant adaptive success (Heil 2008;Thadeo et al 2008). A gas chromatography-mass spectrometry (GC-MS) analysis of the metabolomic profiles of expanding floral buds of 16 trees (12 females and 4 males) from two Populus species (Populus deltoides and Populus nigra) was conducted to determine whether secondary metabolites were correlated with gender (Table 2).…”