Biossíntese de lignina em plantas submetidas a déficit

Abstract

In ecosystems, plants are subjected to many potential enemies, both biotic and abiotic. However, vegetables through mutation, natural selection, and evolution developed defense mechanisms changes not only structural but also the metabolic level, which resulted in the appearance of toxic compounds, and more insulating retardants, which have been transferred to their descendants. These compounds are classified as secondary metabolites which are divided into three groups: terpenes, phenolic compounds, and nitrogen compounds. The group of phenolic compounds is the most heterogeneous among the compounds of this group lignin is the most abundant substance in the plant, second only to cellulose. This phenolic macromolecule has a complex branching in three dimensions, but the overall constitution is formed by coniferyl, coumaryl alcohols, and sinapil. Lignin provides greater structural rigidity, durability of fabrics, water transport in xylem vessels and acts as a obstacle the pathogenic action, however, little is known about this dynamic. It is believed that complex genetic and physiological controls act by modulating the expression of genes of lignin and their responses to drought vary depending on the species and the intensity and duration of stress, in which the responses of enzymes could be expressed alone or together with the same kinetics or not. The elucidation of the biosynthesis of lignin contribute to the improvement programs, formulation of mathematical models and for better management of rangelands.