Abstract
Lignin, the second most abundant biopolymer, is a promising renewable energy source and chemical feedstock. A key element of lignin biosynthesis is unknown: how do lignin precursors (monolignols) get from inside the cell out to the cell wall where they are polymerized? Modeling indicates that monolignols can passively diffuse through lipid bilayers, but this has not been tested experimentally. We demonstrate significant monolignol diffusion occurs when laccases, which consume monolignols, are present on one side of the membrane. We hypothesize that lignin polymerization could deplete monomers in the wall, creating a concentration gradient driving monolignol diffusion. We developed a two-photon microscopy approach to visualize lignifying Arabidopsis thaliana root cells. Laccase mutants with reduced ability to form lignin polymer in the wall accumulated monolignols inside cells. In contrast, active transport inhibitors did not decrease lignin in the wall and scant intracellular phenolics were observed. Synthetic liposomes were engineered to encapsulate laccases, and monolignols crossed these pure lipid bilayers to form polymer within. A sink-driven diffusion mechanism explains why it has been difficult to identify genes encoding monolignol transporters and why the export of varied phenylpropanoids occurs without specificity. It also highlights an important role for cell wall oxidative enzymes in monolignol export.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 7
Claim · model-written summary
Laccases on one membrane side enabled significant monolignol diffusion.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianat0 - Gene
- laccasese0
- Outcome
- monolignol diffusione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant monolignol diffusion occurs when laccases, which consume monolignols, are present on one side of the membrane”
t0“Arabidopsis thaliana”
Claim · model-written summary
A two-photon microscopy approach visualized lignifying Arabidopsis root cells.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- visualize lignifying Arabidopsis thaliana root cellse0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We developed a two-photon microscopy approach to visualize lignifying Arabidopsis thaliana root cells”
t0“Arabidopsis thaliana”
Claim · model-written summary
Laccase mutants accumulated monolignols inside cells.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Material
- Laccase mutantse0
- Outcome
- accumulated monolignols inside cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Laccase mutants with reduced ability to form lignin polymer in the wall accumulated monolignols inside cells”
t0“Arabidopsis thaliana”
Claim · model-written summary
Active transport inhibitors did not decrease cell-wall lignin.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- active transport inhibitorse0
- Outcome
- lignin in the walle0
- Direction
- did not decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“active transport inhibitors did not decrease lignin in the wall”
t0“Arabidopsis thaliana”
Claim · model-written summary
Scant intracellular phenolics were observed with transport inhibitors.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- active transport inhibitorse0
- Outcome
- scant intracellular phenolicse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“active transport inhibitors did not decrease lignin in the wall and scant intracellular phenolics were observed”
t0“Arabidopsis thaliana”
Claim · model-written summary
Monolignols crossed pure lipid bilayers of laccase liposomes and polymerized within.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Gene
- laccasese0
- Outcome
- monolignols crossed these pure lipid bilayers to form polymer withine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Synthetic liposomes were engineered to encapsulate laccases, and monolignols crossed these pure lipid bilayers to form polymer within”
t0“Arabidopsis thaliana”
Claim · model-written summary
A sink-driven diffusion mechanism explains monolignol export without transporter specificity.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- export of varied phenylpropanoids occurs without specificitye0
- Qualifier
- sink-driven diffusion mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A sink-driven diffusion mechanism explains why it has been difficult to identify genes encoding monolignol transporters and why the export of varied phenylpropanoids occurs without specificity”
t0“Arabidopsis thaliana”