Seasonal and spatial variation of the iridoid specioside in monodominant formation of Tabebuia aurea in the Brazilian Pantanal wetland/ Variação sazonal e espacial do especiosídeo iridóide em formação monodominante de Tabebuia aurea na zona húmida do Pantanal brasileiro

Abstract

It is common in the Pantanal the occurrence of monodominant formations, such as “paratudal” dominated by Tabebuia aurea. Although it is of high importance, little is known about how it is maintained and what factors limit its progress. We investigated the variation of secondary metabolism between individuals located on the edge and center of the formation as well as the effect of flood pulse and what part of the plant (stem bark or leaves) is there greater accumulation of iridoids glycosides, and if is there a translocation of specioside between them. We collected stem bark and leaves samples from individuals of T. aurea located in the center and edge of paratudal in drought and flooded season, sampled individuals were the same in both seasons. We also analyzed the topographic profile of paratudal. Ours results showed that the specioside concentration in stem bark decreased during flood season only on the edge of paratudal and this region was lower than the center. Individuals located on the edge stay more time exposed to the flooding effect. These results suggest that the flooding is the main cause of the change in the specioside concentration on monodominant formation and the topography should delimitate the monoformation