Population: Vanilla orchid plants
Duration: 12 days
Methods: Controlled experimental study
Outcomes: Chloroplast movement, photosynthetic efficiency, antioxidant enzyme activity, carbohydrate accumulation, gene expression related to photosynthesis, biomass.
Results: Blue light acclimation increased photosynthesis rate and biomass under high light stress.
See PDF ijms-21-08022.pdf
This research demonstrates that Vanilla planifolia, a shade-adapted tropical crop sensitive to high irradiance, exhibits chloroplast avoidance movement initiated at blue light (BL) intensities exceeding 20 μmol m⁻²s⁻¹, with significant repositioning observed at 100 μmol m⁻²s⁻¹ (BL100). Under high irradiance (1000 μmol m⁻²s⁻¹), non-acclimated plants showed negligible electron transport rates (ETR) and photochemical quenching (qP).
Twelve-day BL100 pretreatment induced acclimation, characterized by strategic chloroplast repositioning that reduced light-harvesting antenna size and eliminated photodamage. This acclimation enhanced tolerance to moderate (500 μmol m⁻²s⁻¹) and high (1000 μmol m⁻²s⁻¹) light conditions.
BL-acclimated plants maintained superior photosynthetic capacity under high irradiance through multiple mechanisms: enhanced antioxidant enzyme activity, reduced reactive oxygen species accumulation, and increased carbohydrate synthesis. Molecular analysis revealed upregulation of photosystem II-associated genes (D1, PetC), Rubisco, and PEPC transcripts, resulting in maximized photosynthetic rates and increased biomass.
The findings suggest that BL pretreatment before field transplantation could mitigate photoinhibition and enhance vanilla productivity in commercial cultivation.