Histochemistry and ultrastructure of Campuloclinium chlorolepis (Asteraceae) tuberous roots accumulating fructan: evidences of functions other than reserve carbohydrate

Abstract

Campuloclinium chlorolepis (Baker), an herbaceous species of the Cerrado, accumulates inulin-type fructans in the tuberous roots. Plants were collected in the Cerrado and the roots analysed using light and scanning electron microscopy. The presence of fructans was assessed by specific stain reactions and by high performance anion exchange chromatography. Here, we report the localisation of protein, phenols and neutral polysaccharides in the tuberous roots after staining with different dyes generally used in cytochemical analyses. Results showed the presence of fructans inside and outside cells from all tissues of tuberous roots with the exception of the epidermis. When visualised by scanning electron microscopy, globular bodies consistent with typical inulin spherocrystals were clearly detected under polarised light. These globular bodies varied in size according to location, being smaller in the cortical tissue and larger in the central cylinder. The localisation of fructans outside the cell in several tissues of the tuberous roots clearly shown by histochemical and ultrastructural analyses lead to the hypothesis of interaction of fructose polymers with cell membrane and possibly their role in membrane stabilisation in plants subjected to stressing environmental conditions.

Anatomy and fructan distribution in vegetative organs of Dimerostemma vestitum (Asteraceae) from the campos rupestres

“…Thus the predominance of parenchyma cells in the core region of the xylopodium, enabling storage of high amounts of inulin, is consistent with the accumulation of these soluble carbohydrates in the vacuoles of living cells (Darwen and John 1989). Although most plants store sucrose and starch in the reserve organs, the latter has not been identified in D. vestitum, which highlights the importance of fructan accumulation in the adaptation of species from environments such as the campos rupestres (Vilhalva et al 2011).…”

“…Inulin sphero-crystals were also distributed in the parenchyma cells of secondary vascular tissue in the xylopodium of D. vestitum. The location of fructans in vascular tissues as already documented for other species , the rapid polymerization and depolymerization process of such polysaccharides (Pollock 1986) and their adherence to cell walls, as in C. chlorolepis (Vilhalva et al 2011) provide evidences that fructans may play important roles in the adaptation of species to campos rupestres, as it has been proposed for other Cerrado physiognomies with fire occurrence (Gomes et al 2014) and unfavorable conditions of soil, water and temperature (Dias-Tagliacozzo et al 1999, Portes et al 2008). …”

“…In Asteraceae, inulin crystals were found in the medulla and xylem parenchyma in 70% of the species analyzed in a restricted cerrado area (Tertuliano and Figueiredo-Ribeiro 1993), in the cortical parenchyma of C. chlorolepis tuberous roots (Vilhalva et al 2011) and in the rhizophores of V. herbacea and V. platensis (Hayashi and Appezzato-da-Gloria 2005). Inulin sphero-crystals were also distributed in the parenchyma cells of secondary vascular tissue in the xylopodium of D. vestitum.…”

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

“…The presence of fructans, rather than starch or sucrose, is an adaptive characteristic of some Cerrado plants, especially herbaceous species (Vilhalva et al 2011). Fructans play a key role in osmotic regulation, which permits the survival and development of such species in environments with poor water availability (Brocklebank and Hendry 1989, Figueiredo-Ribeiro 1993, Valluru and Van den Ende 2008, Vilhalva et al 2011.…”

“…The presence of fructans, rather than starch or sucrose, is an adaptive characteristic of some Cerrado plants, especially herbaceous species (Vilhalva et al 2011). Fructans play a key role in osmotic regulation, which permits the survival and development of such species in environments with poor water availability (Brocklebank and Hendry 1989, Figueiredo-Ribeiro 1993, Valluru and Van den Ende 2008, Vilhalva et al 2011. Therefore, the ability to metabolise and use fructans rapidly when environmental conditions become favourable could be advantageous to plants that accumulate these polysaccharides and that are adapted to survive under transient drought conditions (Figueiredo-Ribeiro 1993).…”