Bracken adaptation mechanisms and xenobiotic chemistry

Abstract

As opposed to animals, plants have to cope with the resources, environmental restrictions, herbivores, and pathogens they find in the particular spot where they are bound to grow. Hence, resource sequestration, predation and competition relationships, and adaptation to various sources of other environmental stresses and their seasonal variation must be flexible enough to ensure survival and successful reproduction. Plants express this fitness by a combination of biological traits and chemical arsenals which operate under the reign of a genome of considerable plasticity. For the great majority of plants it is either the biological characters or the chemical composition that are explored independently to understand their fitness. But only in a few instances is the combination of these two avenues examined jointly. The extensive studies on the ecology, chemistry, and toxicology of bracken (Pteridium aquilinum) make this fern one of the few examples where a reasonable explanation for its extraordinary success is beginning to emerge by the combined perception of these two most important aspects of plant life. It is the purpose of this article to briefly review how the sum of biological and chemical traits cooperates to make of bracken one of the five most pernicious weeds in the world today.

Phenolics and condensed tannins in relation to altitude in neotropical Pteridium spp

“…Also, while northern bracken in New Jersey has no phenolic material in the crozier (Tempel, 1981), our samples contained substantial amounts of both types of phenolics in this stage. Such quantities may confer sufficient protection against predation in our area, accompanied by other defense substances also found in significant quantities in the young fiddleheads, such as a cyanogenic glycoside-prunasin-, carcinogenic and toxic ptaquiloside and other xenobiotics (Alonso-Amelot et al, 2001). But increased protection based on phenolics with frond growth is not compatible with an exclusive defensive role of these compounds.…”

Phenolics and condensed tannins of high altitude Pteridium arachnoideum in relation to sunlight exposure, elevation, and rain regime

“…The reduced phenolics-based defense capacity is counterbalanced by other xenobiotics in high concentration in the crozier such as prunasin, a cyanogenic glycoside, and illudanes. Their levels wane with frond growth as phenolics contents increases (Alonso-Amelot et al, 2001;Alonso-Amelot and Oliveros-Bastidas, 2005b). The fronds growing at high altitude seem to invert the trend of phenolic accumulation in non herbivore-stressed plants.…”

“…responded to altitude during the rainy season by increasing its content of high molecular weight phenolics (HMP) only at elevations greater than 2600 m above sea level (Alonso-Amelot et al, 2004). In a continued effort to understand the various biological and chemical traits that make Pteridium ferns among the most dominant plants in the world (Alonso-Amelot et al, 2001;Alonso-Amelot, 2002), we pursued further dynamics of their LMPeHMP load in order to evaluate the effects of season (rain regime and cloudiness), altitude in exposed and self shaded pinnae, and the position of each pinnae relative to the axis of the blade (rachis) in dense high altitude thickets of tropical P. arachnoideum, under field conditions.…”

A vegetação da Estação Ecológica de Avaré: subsídios para o plano de manejo

“…Entre elas, destaca-se a espécie Pteridium aquilinum (L) Kuhn, por suas propriedades carcinogênicas para animais (Shahin et al, 1999;Alonso-Amelot et al, 2001). Propriedade semelhante foi encontrada na samambaia-do-campo, P. arachnoideum.…”