Effect of Modification of the O-Methyltransferase Activity on Cell Wall Composition, Ultrastructure and Degradability of Transgenic Tobacco

Vailhé, Marie Andrée Bernard; Migné, Carole; Cornu, Agnès; Maillot, Marie Paule; Grenet, Élisabeth; Besle, J.M.; Atanassova, Rossitza; Martz, Françoise; Legrand, Michel

doi:10.1002/(sici)1097-0010(199611)72:3<385::aid-jsfa664>3.3.co;2-c

Cited by 5 publications

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“…In these systems, lignin structures can be modified by altering the expression of genes coding for enzymes in the lignin biosynthesis pathway, or by chemically modifying the lignin as it polymerizes in the cell wall. Previous studies have used genetically or chemically modified plant systems in laboratory studies to examine lignin chemistry effects on cell wall degradation by rumen microbes (Grabber 2005;Grabber et al 2009;Jung and Casler 1991;Jung and Buxton 1994;Jung et al 1999;Vailhe et al 1996), extracellular enzyme preparations (Grabber 2005;Grabber et al 1998c;Grabber et al 1997;Li et al 2010), or microbes in soil microcosms (Hénault et al 2006;Machinet et al 2009;Webster et al 2005). These studies have found mixed evidence for the hypothesis that lignin chemical composition affects plant cell wall degradation.…”

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confidence: 99%

Litter decay rates are determined by lignin chemistry

et al. 2011

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Litter decay rates are often correlated with the initial lignin:N or lignin:cellulose content of litter, suggesting that interactions between lignin and more labile compounds are important controls over litter decomposition. The chemical composition of lignin may influence these interactions, if lignin physically or chemically protects labile components from microbial attack. We tested the effect of lignin chemical composition on litter decay in the field during a year-long litterbag study using the model system Arabidopsis thaliana. Three Arabidopsis plant types were used, including one with high amounts of guaiacyl-type lignin, one with high aldehyde-and phydroxyphenyl-type lignin, and a wild type control with high syringyl-type lignin. The high aldehyde litter lost significantly more mass than the other plant types, due to greater losses of cellulose, hemicellulose, and N. Aldehyde-rich lignins and p-hydroxyphenyl-type lignins have low levels of cross-linking between lignins and polysaccharides, supporting the hypothesis that chemical protection of labile polysaccharides and N is a mechanism by which lignin controls total litter decay rates. 2D NMR of litters showed that lignin losses were associated with the ratio of guaiacyl-to-p-hydroxyphenyl units in lignin, because these units polymerize to form different amounts of labile-and recalcitrant-linkages within the lignin polymer. Different controls over lignin decay and polysaccharide and N decay may explain why lignin:N and lignin:cellulose ratios can be better predictors of decay rates than lignin content alone.

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Section: Introductionmentioning

confidence: 99%

Litter decay rates are determined by lignin chemistry

et al. 2011

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Opportunities to improve fiber degradation in the rumen: microbiology, ecology, and genomics

et al. 2003

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The degradation of plant cell walls by ruminants is of major economic importance in the developed as well as developing world. Rumen fermentation is unique in that efficient plant cell wall degradation relies on the cooperation between microorganisms that produce fibrolytic enzymes and the host animal that provides an anaerobic fermentation chamber. Increasing the efficiency with which the rumen microbiota degrades fiber has been the subject of extensive research for at least the last 100 years. Fiber digestion in the rumen is not optimal, as is supported by the fact that fiber recovered from feces is fermentable. This view is confirmed by the knowledge that mechanical and chemical pretreatments improve fiber degradation, as well as more recent research, which has demonstrated increased fiber digestion by rumen microorganisms when plant lignin composition is modified by genetic manipulation. Rumen microbiologists have sought to improve fiber digestion by genetic and ecological manipulation of rumen fermentation. This has been difficult and a number of constraints have limited progress, including: (a) a lack of reliable transformation systems for major fibrolytic rumen bacteria, (b) a poor understanding of ecological factors that govern persistence of fibrolytic bacteria and fungi in the rumen, (c) a poor understanding of which glycolyl hydrolases need to be manipulated, and (d) a lack of knowledge of the functional genomic framework within which fiber degradation operates. In this review the major fibrolytic organisms are briefly discussed. A more extensive discussion of the enzymes involved in fiber degradation is included. We also discuss the use of plant genetic manipulation, application of free-living lignolytic fungi and the use of exogenous enzymes. Lastly, we will discuss how newer technologies such as genomic and metagenomic approaches can be used to improve our knowledge of the functional genomic framework of plant cell wall degradation in the rumen.

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