Comparative analysis of leaf cell-wall polysaccharides of Dialypetalanthus fuscescens and Bathysa meridionalis: evidence of biochemical similarities between Dialypetalanthaceae and Rubiaceae-Cinchonoideae

Abstract

-(Comparative analysis of leaf cell-wall polysaccharides of Dialypetalanthus fuscescens and Bathysa meridionalis: evidence of biochemical similarities between Dialypetalanthaceae and Rubiaceae-Cinchonoideae). Dialypetalanthus fuscescens is an Amazonian endemic species with problematic taxonomic position. This neotropical rainforest tree belongs to the monospecific Dialypetalanthaceae. In the present work, we analysed the leaf cell-wall polysaccharide composition of Dialypetalanthus fuscescens and compared it to that of Bathysa meridionalis (Rubiaceae-Cinchonoideae). Glycosyl composition and glycosyl-linkage analysis indicated that both species have similar cell wall composition. Arabinogalactans were the major component of the pectic polysaccharides and xylans, although being reported in minor amounts in dicots, were found to be the predominant hemicellulosic polysaccharide in cell walls of both species. These findings are in agreement with previous data on cell wall composition reported for Rubiaceae and corroborate the current suggestion of the possible link between this family and Dialypetalanthaceae.RESUMO -(Análise comparativa de polissacarídeos de paredes celulares de folhas de Dialypetalanthus fuscescens e Bathysa meridionalis: evidências de similaridades bioquímicas entre Dialypetalanthaceae e Rubiaceae-Cinchonoideae). Dialypetalanthus fuscescens é uma espécie endêmica da Amazônia com posição taxonômica incerta. Esta espécie da floresta úmida neotropical pertence à família monoespecífica Dialypetalanthaceae. Neste trabalho, foi analisada a composição dos polissacarídeos de paredes celulares de folhas de Dialypetalanthus fuscescens e esta comparada com Bathysa meridionalis (RubiaceaeCinchonoideae). Análises de composição química e ligações glicosídicas demonstraram que ambas as espécies possuem composição química da parede celular bastante similar. Arabinogalactanos foram identificados como os polissacarídeos pécticos predominantes e os xilanos, embora menos freqüentes em dicotiledôneas, foram encontrados em grandes quantidades na fração hemicelulósica de ambas as espécies. Esses resultados estão de acordo com outros previamente reportados para Rubiaceae e constituem uma evidência adicional da possível proximidade taxonômica de Dialypetalanthaceae com Rubiaceae, como atualmente aceito.

Cell wall polysaccharides from cell suspension cultures of the Atlantic Forest tree Rudgea jasminoides (Rubiaceae)

“…However, they were shown to predominate in leaf cell walls of three woody Rubiaceae species from tropical environment, and also in the monospecific Dialypetalanthaceae (Braga et al 1998;Moraes et al 2001), which is suggested to be closely related to Rubiaceae (Piesschaert et al 1997). Therefore, the analysis of primary cell walls from suspension culture of R. jasminoides confirmed the previous suggestion that arabinoxylan occurs in a proportion that is higher than what has been usually reported for primary cell walls of most eudicots (Carpita and Gibeaut 1993).…”

“…About 5 mg of EP and all cell-wall fractions from 14-dayold cultures were applied to a 1.5-9 97.0-cm column of Sepharose 4B (Pharmacia) equilibrated with 150 mmol L -1 Na citrate-phosphate, pH 5.2 (McIlvaine) (Moraes et al 2001). Dextrans of 9.3, 156 and 2,000 kDa were used as standards for column calibration.…”

“…Studies about the cell wall composition of tropical tree species belonging to the Asteridae, where the family Rubiaceae is included, are scarce in the literature (Braga et al 1998), except for the observations by Braga et al (1998) and Moraes et al (2001) that xylans were shown to predominate in leaf cell walls of three Rubiaceae species from tropical environment, including R. jasminoides. Whether or not the predominance of this polymer in some Rubiaceae could be explained, at least in part, by the presence of secondary cell walls commonly found in leaf tissues, this finding might suggest that xylans, instead of xyloglucans, account for most of the leaf cross-linked glycans found in the Rubiaceae.…”

Chemistry and Biological Activity of Condamineeae Tribe: A Chemotaxonomic Contribution of Rubiaceae Family

“…The analyses demonstrated both species have very similar chemical composition of the cell wall corroborating as additional evidence of their taxonomic proximity as is actually accepted [49]. In addition to studies that classify the genus on Ixoroideae subfamily and Condamineeae tribe through molecular phylogenetical investigations [3] [5] [11].…”

Differences in the cell walls and extracellular polymers of the two Trebouxia microalgae coexisting in the lichen Ramalina farinacea are consistent with their distinct capacity to immobilize extracellular Pb

“…About 5 mg of EPS was applied to a 1.0 × 40.0 cm column of Sepharose 4B (Pharmacia) equilibrated with 150 mM Na citratephosphate, pH 5.2 [50]. Elution was performed with the same buffer and 2 ml fractions were collected.…”