Innumerous strategies have been developed to optimize the cell wall composition in plants aiming to improve its agro-industrial value. In respect to the use of forages as feedstuff for animals, the lignification resultant from the advance in maturity is an important limitation to increase productivity in the Brazilian cattle industry. Despite the undeniable importance of forages to ruminant production in Brazil, there is no published study with altered lignin synthesis in tropical forages. Several temperate climate plants, such as tobacco, arabidopsis, alfalfa and maize, have been used in studies where the expression of enzymes important for monolignols synthesis, the precursors of lignin, were altered. In these studies, the silencing of the enzymes resulted in lower lignin content and higher ruminal digestibility for the plants.The objective of this work is to generate an information base aiming to understand the genes involved with lignin synthesis and with lignin-cell wall cross-linking, which reduces the carbohydrate digestibility. Specifically, it is our objective to clone and sequence the main enzymes involved with the metabolic pathway of lignin synthesis in Panicum maximum. Moreover, we will characterize the gene expression pattern of these enzymes during the forage development.The genes will be amplified by PCR using specific primers designed based on conserved sequences among ortholog genes that are already available in the GenBank database. After amplification, the PCR product will be inserted in competent cells and sequenced. The gene expression profile of the enzymes involved in lignification will be determined in quantitative PCR using the SYBR Green dye as a marker of DNA.The collected samples will be analyzed for lignin content and composition, and ruminal digestibility. The correlation between gene expression, lignification, lignin composition and ruminal digestibility will allow the identification of steps in the lignin biosynthesis pathway with high potential to restrict ruminal digestibility, which will be used as candidate genes in future studies aiming to manipulate the lignification process in tropical forages.
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