Laccases and Peroxidases Co-Localize in Lignified Secondary Cell Walls throughout Stem Development
Bibliographic record
Abstract
Lignin, a critical phenolic polymer in secondary cell walls of plant cells, enables strength in fibers and water transportation in xylem vessel elements. Secreted enzymes, namely laccases (LACs) and peroxidases (PRXs), facilitate lignin polymerization by oxidizing lignin monomers (monolignols). Previous work in Arabidopsis (Arabidopsis thaliana) demonstrated that AtLAC4 and AtPRX64 localized to discrete lignified cell wall domains in fibers, although the spatial distributions of other enzymes in these large gene families are unknown. Here, we show that characteristic sets of putative lignin-associated LACs and PRXs localize to precise regions during stem development, with LACs and PRXs co-occurring in cell wall domains. AtLAC4, AtLAC17, and AtPRX72 localized to the thick secondary cell wall of xylem vessel elements and fibers, whereas AtLAC4, AtPRX64, and AtPRX71 localized to fiber cell corners. Interestingly, AtLAC4 had a transient cell corner localization early in fiber development that disappeared in the mature stem. In contrast with these secondary cell wall localizations, AtLAC10, AtPRX42, AtPRX52, and AtPRX71 were found in nonlignified tissues. Despite ubiquitous PRX occurrence in cell walls, PRX oxidative activity was restricted to lignifying regions during development, which suggested regulated production of apoplastic hydrogen peroxide. Relative amounts of apoplastic reactive oxygen species differed between lignified cell types, which could modulate PRX activity. Together, these results indicate that precise localization of oxidative enzymes and differential distribution of oxidative substrates, such as hydrogen peroxide, provide mechanisms to control spatiotemporal deposition of lignin during development.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".