Blue Light Mediates Chloroplast Avoidance and Enhances Photoprotection of Vanilla Orchid

Abstract

Vanilla orchid, which is well-known for its flavor and fragrance, is cultivated in tropical and subtropical regions. This shade-loving plant is very sensitive to high irradiance. In this study, we show that vanilla chloroplasts started to have avoidance movement when blue light (BL) was higher than 20 μmol m−2s−1 and significant avoidance movement was observed under BL irradiation at 100 μmol m−2s−1 (BL100). The light response curve indicated that when vanilla was exposed to 1000 μmol m−2s−1, the electron transport rate (ETR) and photochemical quenching of fluorescence (qP) were significantly reduced to a negligible amount. We found that if a vanilla orchid was irradiated with BL100 for 12 days, it acquired BL-acclimation. Chloroplasts moved to the side of cells in order to reduce light-harvesting antenna size, and chloroplast photodamage was eliminated. Therefore, BL-acclimation enhanced vanilla orchid growth and tolerance to moderate (500 μmol m−2s−1) and high light (1000 μmol m−2s−1) stress conditions. It was found that under high irradiation, BL-acclimatized vanilla maintained higher ETR and qP capacity than the control without BL-acclimation. BL-acclimation induced antioxidant enzyme activities, reduced ROS accumulation, and accumulated more carbohydrates. Moreover, BL-acclimatized orchids upregulated photosystem-II-associated marker genes (D1 and PetC), Rubisco and PEPC transcripts and sustained expression levels thereof, and also maximized the photosynthesis rate. Consequently, BL-acclimatized orchids had higher biomass. In short, this study found that acclimating vanilla orchid with BL before transplantation to the field might eliminate photoinhibition and enhance vanilla growth and production.

Anthocyanins: Biosynthesis, Distribution, Ecological Role, and Use of Biostimulants to Increase Their Content in Plant Foods—A Review

“…Moreover, anthocyanins are also involved in response to biotic stresses, such as mechanical damage due to herbivore For these reasons, recently, anthocyanin role in plants was questioned. To date, it is well-known that these molecules are involved in several defensive processes, including the screen role against UV-B [ [45][46][47][48][49] and plant protection against high light intensities [46,49,50]. However, light stresses are not the only abiotic stress in which anthocyanins seem to play a key role.…”

The Mechanisms of Different Light Supply Patterns in the Nutrient Uptake and Chlorophyll Fluorescence of Hydroponic Lettuce

“…On the one hand, we can avoid the excessive absorption of light energy in plants by (a) changing the angle between leaves to reduce excessive absorption of light energy; and (b) promotingthe dark movement of chloroplasts. Under strong light, chloroplasts aggregate on cell walls parallel to the direction of light to reduce light absorption [42,43]. Plants can also avoid excessive light absorption by (c) absorbing or filtering out strong visible and ultraviolet light through phenolic compounds such as anthocyanins, thereby reducing the intensity of the light reaching chloroplasts, thus reducing light inhibition.…”

Photosynthetic and Morphological Responses of Sacha Inchi (Plukenetia volubilis L.) to Waterlogging Stress

“…We measured chlorophyll fluorescence with the portable photosynthesis system (LI-6800F, Li-Cor, Lincoln, NE, USA) as described previously [30]. The instrument was equipped with a fluorescence leaf chamber (6800-01A, Li-Cor), using a 6 cm 2 aperture for the fluorometer.…”