Substâncias antifúngicas constitutivas e induzidas em folhas e suspensões celulares de Rudgea jasminoides (Cham.) Müll. Arg. (Rubiaceae)

Rudgea jasminoides (Cham.) Mull. Arg. is a woody Rubiaceae species from tropical forest that synthesized antifungal secondary metabolites when challenged by fungi. Members of the Rubiaceae are among the few plants that are easily taken into cell cultures to produce substantial amounts of secondary products that surpass those of the whole plant. In this work we analyzed the presence of constitutive and induced antifungal compounds produced by leaves and cell suspension cultures of this species. Oligogalacturonides (OGAs), salicylic acid (AS), nitric oxide (NO), and yeast β-glucan fragments were used as elicitors. Constitutive compounds with antifungal activity were detected in cell suspension cultures of R. jasminoides, mainly during the stationary growth phase. They were found in higher diversity and amounts than those present in leaves. Treatment with β-glucan fragments increased the production of constitutive compounds and induced the synthesis of antifungal metabolites absent in non-elicited cultures (phytoalexins), mainly during the exponential growth phase. OGAs derived from R. jasminoides leaf cell walls showed similar effect. Under our experimental conditions, the endogenous signaling molecules salicylic acid and nitric oxide were toxic to the cells and did not act as elicitors of antifungal compounds in suspension cultures of R. jasminoides. Our data indicate that cell suspension cultures of R. jasminoides are able to synthesize antifungal compounds and their production can be enhanced by fungal or plant elicitors.