Molecular basis of structural studies, phytochemical characterization and nutritional evaluation of new modified alfalfa in ruminant livestock systems

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Alfalfa is one of the most important forages in the world. Alfalfa is a relatively winter hardy and drought tolerant legume with good longevity, has high nutrient levels and digestibility and a unique ratio of structural to non-structural components. A major disadvantage of alfalfa is its excessively rapid initial rate of ruminal protein digestion. This results in serious digestive disorders such as frothy bloat and low protein efficiency with consequent release of upto 25% of alfalfa N from the ruminant into the environment. Characteristic bloat-free legume forage has proanthocyanidins (PA). This feature decreases the initial rate of protein degradation. PA-protein complexes are formed in the rumen, reducing protein degradation and consequently increasing ruminal escape protein and reducing foam stability. PA-protein bonds are broken in the abomasum due to low pH, which results in increased amino acid digestion in the small intestine. PA are also found to reduce the production of methane. Therefore, alfalfa that produces moderate amounts of forage PA would be extremely beneficial for ruminant livestock producers. "Lc" is a maize anthocyanin regulatory gene which forms a ß-Helix-Loop-Helix (bHLH) protein. bHLH proteins normally bind together a MYB protein and a WD-40 protein to form a complex that stimulates the transcription of anthocyanidin and proanthocyanidin biosynthetic genes. This year (2009), new gene-modified "C1-Lc Alfalfa" genotypes expressing C1 and Lc genes became available. The combination of the two genes in "C1-Lc alfalfa" forage should result in much higher titres of anthocyanidins and proanthocyanidins than possible with "Lc-Alfalfa" (with single gene). "ULIMYC-Alfalfa" is a 2nd new genotype of alfalfa and contains a proanthocyanidin-related bHLH gene from a forage legume, big trefoil, rather than from more distantly related cereal, maize. The objective of the research in the next five years is to attain a comprehensive understanding of the single and dual gene transformation (gene combination) that influences alfalfa's intrinsic structure on a molecular basis, N metabolism, microbial N accumulation and the efficiency of N utilization in ruminant livestock systems.