THE UTILIZATION OF CARBON-1 COMPOUNDS BY PLANTS: I. THE METABOLISM OF METHANOL-C¹⁴AND ITS ROLE IN AMINO ACID BIOSYNTHESIS

Abstract

Methanol-C14was rapidly metabolized by carrot tissue slices, pea cotyledons, soybean cotyledons, castor bean endosperm, beet storage tissues, and mature beet leaves. With the exception of beet storage tissues, carbon dioxide was a chief product of methanol metabolism. In all tissues, methanol carbon was also incorporated in the organic acids, sugars, amino acids, and the insoluble residue. Serine, methionine, methionine sulfone, and methionine sulfoxide were important labelled components present in the amino acid fractions separated. Degradation of the serine-C14that was produced by carrot tissues metabolizing methanol-C14showed that the bulk of the label was present in the 3-position. The results are interpreted as indicating that methanol can act as a precursor of the carbon-1 units that are to be utilized in transmethylation reactions leading to serine and methionine biosynthesis. In addition, methanol can be oxidized to carbon dioxide by these tissues, and this reaction possibly involves dehydrogenase systems.

Enhanced Formaldehyde Detoxification by Overexpression of Glutathione-Dependent Formaldehyde Dehydrogenase from Arabidopsis

“…It has been reported that foliar application of methanol can stimulate plant growth (Nonomura and Benson, 1992) and that methanol is quickly oxidized in most plant tissues successively to formaldehyde, formic acid, and CO 2 (Cossins, 1964). Formaldehyde can be incorporated to plant C1 metabolism mainly by two metabolic pathways that involve folatemediated and -independent reactions (Hanson and Roje, 2001).…”

“…The formate is then incorporated into the C1-tetrahydrofolate pool via the 10-formyl-tetrahydrofolate. In the folate-independent pathway, formaldehyde is successively converted to formic acid and CO 2 , and CO 2 is then assimilated by the Calvin-Benson cycle in the photosynthetic tissues (Cossins, 1964). Formate might also give rise to glyoxylate, in a reaction catalyzed by glyoxylate synthetase that is exclusively found in plants (Janave et al, 1993).…”

“…Formate can give rise to C1 folates, but a quantitatively more important fate is oxidation to CO 2 mediated by formate dehydrogenase (Cossins, 1964). NAD-dependent formate dehydrogenase has been cloned from Arabidopsis, which is predicted to have a mitochondrial and a chloroplastic localization (Olson et al, 2000).…”

Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

“…Other factors that may influence methanol emission rates during leaf development include (a) methanol pool size, which may vary with changing metabolism, and (b) leaf methylotrophic bacterial populations. Since plants are able to metabolize methanol (Cossins, 1964), the amount of methanol emitted from leaves may represent only a fraction of that produced within the leaves. Methanol metabolism in plant cells might change during the course of leaf development.…”

Glutathione-dependent formaldehyde dehydrogenase from golden pothos (Epipremnum aureum) and the production of formaldehyde detoxifying plants

“…Sformylglutathione is then hydrolyzed to formate and glutathione by S-formylglutathione hydrolase. Formate is oxidized to CO 2 by formate dehydrogenase (Cossins 1964). FALDH is expressed at low levels in Arabidopsis (5ϫ10 Ϫ3 units mg…”