Biosynthesis of the Major Tetrahydroxystilbenes in Spruce, Astringin and Isorhapontin, Proceeds via Resveratrol and Is Enhanced by Fungal Infection
Bibliographic record
Abstract
Stilbenes are dibenzyl polyphenolic compounds produced in several unrelated plant families that appear to protect against various biotic and abiotic stresses. Stilbene biosynthesis has been well described in economically important plants, such as grape (Vitis vinifera), peanut (Arachis hypogaea), and pine (Pinus species). However, very little is known about the biosynthesis and ecological role of stilbenes in spruce (Picea), an important gymnosperm tree genus in temperate and boreal forests. To investigate the biosynthesis of stilbenes in spruce, we identified two similar stilbene synthase (STS) genes in Norway spruce (Picea abies), PaSTS1 and PaSTS2, which had orthologs with high sequence identity in sitka (Picea sitchensis) and white (Picea glauca) spruce. Despite the conservation of STS sequences in these three spruce species, they differed substantially from angiosperm STSs. Several types of in vitro and in vivo assays revealed that the P. abies STSs catalyze the condensation of p-coumaroyl-coenzyme A and three molecules of malonyl-coenzyme A to yield the trihydroxystilbene resveratrol but do not directly form the dominant spruce stilbenes, which are tetrahydroxylated. However, in transgenic Norway spruce overexpressing PaSTS1, significantly higher amounts of the tetrahydroxystilbene glycosides, astringin and isorhapontin, were produced. This result suggests that the first step of stilbene biosynthesis in spruce is the formation of resveratrol, which is further modified by hydroxylation, O-methylation, and O-glucosylation to yield astringin and isorhapontin. Inoculating spruce with fungal mycelium increased STS transcript abundance and tetrahydroxystilbene glycoside production. Extracts from STS-overexpressing lines significantly inhibited fungal growth in vitro compared with extracts from control lines, suggesting that spruce stilbenes have a role in antifungal defense.
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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) | 0.000 | 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".