IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
capítulos de libros
Título:
GC and GC-MS of terpenoids
Autor/es:
LÓPEZ M.L; DAMBOLENA J. S.; ZUNINO M. P.; ZYGADLO J.A.
Libro:
Isolation, identification and characterization of allelochemical/natural products. Book series: Research methods in Plant Science: Allelopathy
Editorial:
SCIENCE PUBLISHERS, USA
Referencias:
Lugar: USA; Año: 2007;
Resumen:
Introduction Allelopathy is defined as the effect of one plant on growth and distribution of other plants (including microorganisms) through the release of chemical compounds into the environment. This definition includes not only positive and negative effects, but also direct and indirect effects of plant allelochemicals (Inderjit and Nilsen, 2003). Plant secondary compounds involved in an allelopathic process are known as allelopathic agents. These compounds have been characterized according with their modes of release, phytotoxic action, bioactive concentration and persistence and fate in the environment (Inderjit and Duke, 2003). Terpenes are components of essential oils and accumulate in aromatic plants. They have multiple ecological functions in plants, such as protection against herbivores (Banchio et al., 2005) and microbial diseases, attraction of pollinators and allelopathy (Fisher, 1986; Fisher 1991; Weidenhamer et al., 1993). An allelopathic phenomenon involving terpene compounds comprises the following components (Figure 1):     A) Terpene production Allelochemical production in aromatic plants is usually located in secretory structures as glandular hairs, secretory cavities and ducts. Several environmental and physiological factors affect biosynthesis and accumulation of essential oils (Sangwan et al., 2001). Essential oil composition also changes with geographical location, altitude, intraspecific variation, soil type, nutrient status and phenology (Azevedo et al., 2001; Gil et al., 2000; Graven et al., 1991; Hudaib et al., 2002). B) Release and accumulation Terpene release and accumulation in the environment occur almost sequenced. Release can occur by evaporation (volatilization), leaching, root exudation and decomposition of plant residues in the soil (Dudareva et al., 2004; Walker et al., 2001; An et al., 2001). Accumulation is the outcome of several interacting factors such as edaphic properties, climatic conditions and periodic replenishment of terpenes from donor plants. C) Biological effect Allelopathic effect must be corroborated at field conditions. One of the best ways to ensure that a test for allelopathy reflects natural (field) conditions is to perform a bioassay in situ. However, these assays often provide limited information because allelopathy is only one of the complex interacting processes that simultaneously occur in a natural system (Inderjit and Nilsen, 2003). Laboratory bioassays usually allow a better elucidation of allelopathic mechanisms because the experimental system can be modelled and factors can be kept constant. Studies carried out in the laboratory have provided valuable information about action mechanisms of terpenes on plant physiology (Zunino and Zygadlo, 2005; Zunino et al., 2005).