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Results for “Lignin/biosynthesis/metabolism”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Induced phenylpropanoid metabolism during suberization and lignification: a comparative analysis

Induction of the biosynthesis of phenylpropanoids was monitored at the enzyme level through measurement of the temporal change in the activity of two marker enzymes of phenylpropanoid metabolism, phenylalanine ammonia-lyase, (PAL, E.C. 4.1.3.5) and 4-coumaryl-CoA ligase (4-CL, E.C. 6.2.1.12) and two marker enzymes for hydroxycinnamyl alcohol biosynthesis, cinnamoyl-CoA:NADP+ oxidoreductase (CCR, E.C. 1.2.1.44) and cinnamyl alcohol dehydrogenase (CAD, E.C. 1.1.1.195) in both suberizing potato (Solanum tuberosum) tubers and lignifying loblolly pine (Pinus taeda) cell cultures. While measurable activities of PAL, 4-CL and CAD increased upon initiation of suberization in potato tubers, that of CCR did not. By contrast, all four enzymes were induced upon initiation of lignification in pine cell cultures. The lack of CCR induction in potato by wound treatment is consistent with the channelling of hydroxycinnamoyl-CoA derivatives away from monolignol formation and toward other hydroxycinnamoyl derivatives such as those that accumulate during suberization.

Non-NASA Center↗
NASA NTRS1990

Formation of cis-coniferin in cell-free extracts of Fagus grandifolia Ehrh bark

American beech (Fagus grandifolia Ehrh) bark exclusively accumulates cis-monolignols and their glucosidic conjugates; no evidence for the accumulation of trans-monolignols has been found. The glucosyltransferase from this source exhibits a very unusual substrate specificity for cis, and not trans, monolignols. This is further evidence that cis monolignols are involved in lignin formation in these plant tissues. Preliminary evidence for the existence of a novel trans-cis monolignol isomerase was obtained, in agreement with our contention that this isomerization is not photochemically mediated.

NASA Program Space Biology↗
NASA NTRS1988

4-Coumarate:coenzyme A ligase and isoperoxidase expression in Zinnia mesophyll cells induced to differentiate into tracheary elements

When cultured in inductive medium containing adequate auxin and cytokinin, isolated mesophyll cells of Zinnia elegans L. cv Envy differentiate into tracheary elements with lignified secondary wall thickenings. Differentiation does not occur when cells are cultured in control medium, which has reduced levels of auxin and/or cytokinin. The activities of two enzymes involved in lignin synthesis, 4-coumarate:coenzyme A ligase and peroxidase, were examined. An induction-specific cationic isoperoxidase, visualized by low pH polyacrylamide gel electrophoresis, is detectable in soluble and wall fractions of cultured Zinnia cells long before tracheary elements visibly differentiate and is thus an early marker of differentiation. Compounds (such as antiauxins, anticytokinins, and tunicamycin) that inhibit or delay differentiation alter the expression of this isoperoxidase. 4-Coumarate:coenzyme A ligase activity increases dramatically only as cells differentiate. Together, these results suggest that the onset of lignification in differentiating Zinnia cells might be controlled by the availability of precursors synthesized by way of 4-coumarate:coenzyme A ligase. These precursors would then be polymerized into lignin in the cell wall by the induction-specific isoperoxidase.

NASA Discipline Plant Biology↗