Description
🛡️ Polyvinylpyrrolidone (PVP-40) — anti-browning polymer for TC. Binds polyphenols before they oxidise and toxify the medium — essential for tannin-rich species like walnut, oak, and fruit trees.
| 🧪 CAS | 9003-39-8 | ⚖️ MW | ~40,000 Da |
| 🔬 Grade | TC / Molecular Biology | 🌡️ Storage | RT, dry, sealed |
🛡️ The browning problem explained
When plant tissue is wounded (during explant preparation), cellular polyphenol oxidase (PPO) oxidises polyphenols to quinones, which polymerise to dark brown pigments that diffuse into the medium and are cytotoxic to the explant. PVP forms hydrogen bonds with polyphenol hydroxyl groups, sequestering them before PPO can act.
🛡️ Working concentrations
| Use | Concentration | Notes |
|---|---|---|
| Walnut / Juglans medium | 0.5–1 g/L in medium | DKW or WPM base |
| Oak / Quercus establishment | 0.25–0.5 g/L | Combine with ascorbic acid |
| Fruit tree callus initiation | 0.1–0.5 g/L | Apple, pear, peach |
| Explant wash solution | 0.5–2% PVP in rinse buffer | Pre-culture soak 1h |
| Extraction buffer (DNA/protein) | 1–4% PVP | Removes polyphenol inhibitors |
💡 PVP-40 in medium is most effective during Stage I (establishment). Once cultures are established, you can often reduce or remove PVP in subsequent subcultures as the explant adapts. Also combine with ascorbic acid (100 mg/L) for double anti-oxidant protection.
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