A structural review of foliar glands in Passiflora L. (Passifloraceae)

Abstract

Extrafloral glands in Passifloraceae species have aroused the interest of many researchers because of their wide morphological diversity. The present work analyzed the foliar glands on 34 species of Passiflora from samples containing glands in the petiole and foliar blade fixed in 50% solution of formaldehyde-ethanol-acetic acid and stored in a 70% ethanol solution. For anatomical analyses, part of the material was embedded in Paraplast, longitudinally sectioned and double stained with safranin and astra blue. Scanning electron microscopy analysis was also carried out. To analyze the presence of sugars in the secretion of foliar glands, a glucose strip test was used. Based on the results of morphological, anatomical and glucose strip tests, the foliar secretory glands in Passiflora can be grouped into two categories: Type I glands, defined as nectaries, can be elevated or flattened, and can have a sugar content high enough to be detected by the glucose strip test analysis. Type II glands are elevated and did not show a positive reaction to the glucose strip test. From an anatomical viewpoint, glands characterized as extrafloral nectaries show a multistratified secretory epidermis, typically followed by two flat layers of nectariferous parenchyma with dense content. Internal to these layers, vascular bundles are immersed in the subsecretory parenchyma and terminate in phloem cells. On the other hand, type II glands show a single layer of elongated secretory epidermal cells. Internal to this single layer, parenchyma and vascular tissue with both phloem and xylem elements can be observed. The analyzed species show a wide diversity of gland shape and distribution, and the combined analysis of morphology, anatomy and preliminary tests for the presence of glucose in the exudate in different Passiflora subgenera suggests the occurrence of two categories of glands: nectaries and resin glands.

Unidirectional transitions in nectar gain and loss suggest food deception is a stable evolutionary strategy in Epidendrum (Orchidaceae): insights from anatomical and molecular evidence

“…1 and 2 ) differed from the descriptions available for the cuniculus of Brassavola flagellaris (Laeliinae; [ 10 ]) in the resemblance of this structure to the osmophores identified in the Epidendrum species lined with unicellular trichomes. The presence of reducing sugars in the exudate, however, undoubtedly identified these glands as nectaries [ 29 ]. The nectary type and the absence of trichomes, stomata, or cuticle disruption suggest that nectar is released from nectar-producing cells by cuticular pores [ 30 ].…”

Anatomia foliar em um contexto filogenético de >i<Mascagnia>/i< (Bertero ex DC) Bertero (Malphighiaceae) e gêneros segregados

“…Dentro das angiospermas, os NEFs ocorrem em 110 famílias (Weber et al, 2015), destacando Passifloraceae (Malpighiales) pela importância tanto taxonômica (Killip, 1938;López-Meruvia et al, 1993;Vanderplank, 2000;Cervi, 1997;Ulmer e MacDougal 2004;Krosnick et al, 2009;Souza e Lorenzi, 2012;Mezzonato-Pires et al, 2013, Farias et al, 2016Lemos et al, 2017) como ecológica (Cardoso-Gustavson et al, 2013). Dentre esses trabalhos, Lemos et al (2017) destaca-se pelo estudo extenso das glândulas extraflorais de Passiflora com a análise combinada da morfologia, anatomia e presença de carboidratos no exsudato em diferentes subgêneros (Astrophea, Decaloba, Deidamioides e Passiflora), sugerindo a ocorrência de duas categorias de glândulas, os nectários e as glândulas de resina, que diferem não só pelos produtos, néctar e resina respectivamente, mas também pelas características morfológicas e anatômicas.…”

Ontogênese e histoquí­mica das glândulas foliares em espécies de Passiflora L. pertencentes aos subgêneros Decaloba (DC.) Rchb e Passiflora

“…Passiflora L. é o gênero de angiospermas com o maior número de espécies que possuem NEF's, descritos em cerca 320 espécies (Weber & Keller, 2013). Em virtude disso, ao longo das últimas décadas, diferentes pesquisas vêm abordando a presença dessas glândulas em Passiflora, seja destacando a sua morfoanatomia (Jáuregui & Garcia, 2002;Lemos et al, 2017), a sua ultraestrutura (Durke et al, 1982;Durke, 1983;Lemos, 2017) ou as suas interações ecológicas (Cardoso-Gustavson et al, 2013;Silva et al, 2016).…”

“…Atualmente, a descrição mais completa da morfologia e anatomia de glândulas foliares em Passiflora foi proposta por Lemos et al (2017). Neste trabalho as autoras estudaram a presença de glândulas em 34 espécies do gênero Passiflora, pertencentes aos subgêneros Astrophea, Deidamioides, Decaloba e Passiflora.…”

“…Ademais das análises estruturais, Silva et al (2016) (Durkee, 1982(Durkee, , 1983Rocha et al, 2009;Cardoso-Gustavson et al, 2013;Silva et al, 2016;Lemos et al, 2017).…”