Internal secretory spaces in thickened underground systems of Asteraceae species

Abstract

Secretory structures are present in many vascular plants and have an important ecological role as a plant defence mechanism against herbivors and pathogens. Internal secretory spaces of lipid substances are widespread in the Asteraceae. However, information about the occurrence of these structures in thickened underground systems is sparse, compared with what we know about aerial systems. The main objective of the present paper was to investigate the occurrence, formation and chemical nature of the secretory structures in six Asteraceae species belonging to the following tribes: Eupatorieae (Mikania cordifolia and M. sessilifolia), Mutisiae (Trixis nobilis), Plucheeae (Pterocaulon alopecuroides) and Vernonieae (Vernonia elegans and V. megapotamica). The samples were collected in areas of Cerrado (tropical savanna) in the state of São Paulo, Brazil. The secretory structures found were cortical canals in roots (T. nobilis, P. alopecuroides, V. elegans and V. megapotamica), cortical cavities in roots (M. cordifolia, M. sessilifolia and P. alopecuroides), cavities in the secondary phloem of roots (T. nobilis), cortical cavities in the xylopodium (M. cordifolia, M. sessilifolia, P. alopecuroides and V. megapotamica) and in the underground stem (T. nobilis), and canals in the secondary xylem in the xylopodium (M. cordifolia and M. sessilifolia). Histochemical tests showed the presence of lipid substances in all structures.

Histolocalization of chemotaxonomic markers in Brazilian Vernonieae (Asteraceae)

“…Although not commonly described in the literature, the secretory endodermis has already been documented in underground systems of Vernonieae by Luque et al . (), Hayashi & Appezzato‐da‐Glória (, ) and Cury & Appezzato‐da‐Glória ().…”

“…These secretory structures in Asteraceae take the form of glandular trichomes, canals, cavities, laticifers, idioblasts, hydathodes and glandular appendices (Metcalfe & Chalk, ; Carlquist, ; Lestern & Curtis, ; Castro, Leitão Filho & Monteiro, ). In the tribe Vernonieae, glandular trichomes, idioblasts, cavities and secretory channels have all been described (Castro et al ., ; Appezzato‐da‐Glória et al ., ; Favi et al ., ; Cury & Appezzato‐da‐Glória, ; Appezzato‐da‐Glória et al ., ), although the presence of secretory endodermis is less frequently reported (Luque, Menezes & Semir, ; Appezzato‐da‐Glória et al ., ).…”

Anatomy and essential oil composition of the underground systems of three species ofAldamaLa Llave (Asteraceae)1

“…Another important feature of the underground systems of Asteraceae species is the presence of structures secreting secondary metabolites (Appezzato-da-Gló ria et al 2008b, Cury and Appezzato-da-Gló ria 2009, Fritz and Saukel 2011, Oliveira et al 2013. Several compounds have already been described for Aldama (5 Viguiera), including sesquiterpene lactones and diterpenes with known biological activity (Da Costa et al 1996, Marquina et al 2001, Spring et al 2003, Nicolete et al 2009.…”

Influence of growing conditions on morphological and chemical properties and biological effects of extracts of Arnica montana L.

“…Dobro je poznato da sekretorne strukture koje su prisutne kod viših biljaka imaju važnu ekološku ulogu u odbrani biljaka od biljojeda i patogena (Cury and Appezzato-da-Glória, 2009;Werker, 1993). Sekretorni kanali smešteni u sub-epidermalnoj zoni rizoma arnike, takođe mogu imati ulogu rezervoara etarkog ulja, koje biva oslobođeno samo kada je rizom fizički ozleđen.…”