scholarly journals Blue Light Mediates Chloroplast Avoidance and Enhances Photoprotection of Vanilla Orchid

2020 ◽  
Vol 21 (21) ◽  
pp. 8022
Author(s):  
Swee-Suak Ko ◽  
Chung-Min Jhong ◽  
Yi-Jyun Lin ◽  
Ching-Yu Wei ◽  
Ju-Yin Lee ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Response ◽  
High Irradiance ◽  
Photochemical Quenching ◽  
Marker Genes ◽  
Antioxidant Enzyme Activities ◽  
Light Response Curve ◽  
Ros Accumulation ◽  
Light Harvesting Antenna ◽  
High Irradiation

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.

Comparison between modified exponential model and common models of light-response curve

2013 ◽  
Vol 36 (12) ◽  
pp. 1277-1285 ◽  
Author(s):  
Wei-Ying CHEN ◽  
Zhen-Yong CHEN ◽  
Fu-Yan LUO ◽  
Zheng-Song PENG ◽  
Mao-Qun YU
Keyword(s):  
Response Curve ◽  
Light Response ◽  
Exponential Model ◽  
Light Response Curve

scholarly journals Analysis of the Oxidative Burst and Its Relevant Signaling Pathways in Leptosphaeria maculans—Brassica napus Pathosystem

2021 ◽  
Vol 22 (9) ◽  
pp. 4812
Author(s):  
Cunchun Yang ◽  
W. G. Dilantha Fernando
Keyword(s):  
Cell Death ◽  
Signaling Pathways ◽  
Oxidative Burst ◽  
Defense Mechanisms ◽  
Leptosphaeria Maculans ◽  
Gene Interaction ◽  
Early Response ◽  
Marker Genes ◽  
Ros Accumulation ◽  
Microbe Interactions

An oxidative burst is an early response of plants to various biotic/abiotic stresses. In plant-microbe interactions, the plant body can induce oxidative burst to activate various defense mechanisms to combat phytopathogens. A localized oxidative burst is also one of the typical behaviors during hypersensitive response (HR) caused by gene-for-gene interaction. In this study, the occurrence of oxidative burst and its signaling pathways was studied from different levels of disease severity (i.e., susceptible, intermediate, and resistant) in the B. napus–L. maculans pathosystem. Canola cotyledons with distinct levels of resistance exhibited differential regulation of the genes involved in reactive oxygen species (ROS) accumulation and responses. Histochemical assays were carried out to understand the patterns of H2O2 accumulation and cell death. Intermediate and resistant genotypes exhibited earlier accumulation of H2O2 and emergence of cell death around the inoculation origins. The observations also suggested that the cotyledons with stronger resistance were able to form a protective region of intensive oxidative bursts between the areas with and without hyphal intrusions to block further fungal advancement to the uninfected regions. The qPCR analysis suggested that different onset patterns of some marker genes in ROS accumulation/programmed cell death (PCD) such as RBOHD, MPK3 were associated with distinct levels of resistance from B. napus cultivars against L. maculans. The observations and datasets from this article indicated the distinct differences in ROS-related cellular behaviors and signaling between compatible and incompatible interactions.

The Photosynthesis-Light Response Curve

1992 ◽  
pp. 156-191 ◽  
Author(s):  
Richard J. Geider ◽  
Bruce A. Osborne
Keyword(s):  
Response Curve ◽  
Light Response ◽  
Light Response Curve

The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii)

2004 ◽  
Vol 31 (5) ◽  
pp. 471 ◽  
Author(s):  
Stephen O. Kern ◽  
Mark J. Hovenden ◽  
Gregory J. Jordan
Keyword(s):  
Flux Density ◽  
Response Curve ◽  
Leaf Shape ◽  
Carbon Assimilation ◽  
Light Response ◽  
Light Interception ◽  
Photon Flux ◽  
Assimilation Rate ◽  
Light Response Curve ◽  
Carbon Assimilation Rate

The impact of differences in leaf shape, size and arrangement on the efficiency of light interception, and in particular the avoidance of photoinhibition, are poorly understood. We therefore estimated light exposure of branches in the cool temperate rainforest tree, Nothofagus cunninghamii (Hook.) Oerst., in which leaf shape, size and arrangement vary systematically with altitude and geographic origin. Measurements of incident photosynthetic photon flux density (PPFD) were made in the laboratory at solar angles corresponding to noon at summer solstice, winter solstice and equinox on branches collected from a common garden experiment. Tasmanian plants showed more self-shading than Victorian plants in summer and equinox. This was related to branch angle, leaf arrangement and leaf shape. Using a modelled light response-curve, we estimated the carbon assimilation rate and the flux density of excess photons at different incident PPFD. Victorian plants had higher predicted assimilation rates than Tasmanian plants in summer and equinox, but were exposed to substantially greater levels of excess photons. Because of the shape of the light-response curve, self-shading appears to reduce the plant's exposure to excess photons, thus providing photoprotection, without substantially reducing the carbon assimilation rate. This is dependent on both regional origin and season.

scholarly journals Role of blue and red light in stomatal dynamic behaviour

2019 ◽  
Vol 71 (7) ◽  
pp. 2253-2269 ◽  
Author(s):  
Jack S A Matthews ◽  
Silvere Vialet-Chabrand ◽  
Tracy Lawson
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Light Response ◽  
Early Morning ◽  
Stomatal Opening ◽  
Carbon Gain ◽  
Blue Light Response ◽  
Order Of Magnitude ◽  
Photosynthetic Responses ◽  
Novel Target

Abstract Plants experience changes in light intensity and quality due to variations in solar angle and shading from clouds and overlapping leaves. Stomatal opening to increasing irradiance is often an order of magnitude slower than photosynthetic responses, which can result in CO2 diffusional limitations on leaf photosynthesis, as well as unnecessary water loss when stomata continue to open after photosynthesis has reached saturation. Stomatal opening to light is driven by two distinct pathways; the ‘red’ or photosynthetic response that occurs at high fluence rates and saturates with photosynthesis, and is thought to be the main mechanism that coordinates stomatal behaviour with photosynthesis; and the guard cell-specific ‘blue’ light response that saturates at low fluence rates, and is often considered independent of photosynthesis, and important for early morning stomatal opening. Here we review the literature on these complicated signal transduction pathways and osmoregulatory processes in guard cells that are influenced by the light environment. We discuss the possibility of tuning the sensitivity and magnitude of stomatal response to blue light which potentially represents a novel target to develop ideotypes with the ‘ideal’ balance between carbon gain, evaporative cooling, and maintenance of hydraulic status that is crucial for maximizing crop performance and productivity.

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