|Grabber, John - PROTIVA-MONSANTO CORP.|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 24, 1997
Publication Date: N/A
Technical Abstract: Structural carbohydrates within forage cell walls are a source of energy, yet on average less than 50% are utilized by ruminants. Researchers have sought ways to unlock this store of energy, increasing the economic benefit of forages as ruminant feeds. Lignin concentration is correlated with decreased wall digestibility, yet the underlying mechanisms have not been fully defined. Recent evidence suggests that the cross-linked nature of th wall is as critical, if not more so, than the simple concentration of lignin. Significant advances have been made in determining the molecular nature of wall cross-links and their impact upon wall structure and function. It is now well established that ferulates play a major role in grass wall cross-linking. Work with model systems clearly demonstrates the negative impact of ferulate cross-linking on wall degradation, whereas, simply altering lignin composition has little impact. As our molecular comprehension of wall component interactions increases, the metabolic pathways for their formation are also revealed. Key metabolic steps can be targeted for genetic manipulation, focusing on specific genes to enhance forage quality without sacrificing productivity. Recent structural characterization of lignins formed by plants deficient in coniferyl alcohol dehydrogenase contained unique phenolics not produced by the traditional monolignol pathway. This may open a whole new realm of possibilities for altering forage plants for increased utilization.