Hormetic Responses of Photosystem II in Tomato to Botrytis cinerea

Botrytis cinerea, a fungal pathogen that causes gray mold, is damaging more than 200 plant species, and especially tomato. Photosystem II (PSII) responses in tomato (Solanum lycopersicum L.) leaves to Botrytis cinerea spore suspension application were evaluated by chlorophyll fluorescence imaging analysis. Hydrogen peroxide (H2O2) that was detected 30 min after Botrytis application with an increasing trend up to 240 min, is possibly convening tolerance against B. cinerea at short-time exposure, but when increasing at relative longer exposure, is becoming a damaging molecule. In accordance, an enhanced photosystem II (PSII) functionality was observed 30 min after application of B. cinerea, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in a significant decrease in the dissipated non-regulated energy (ΦNO), indicating a possible decreased singlet oxygen (1O2) formation, thus specifying a modified reactive oxygen species (ROS) homeostasis. Therefore, 30 min after application of Botrytis spore suspension, before any visual symptoms appeared, defense response mechanisms were triggered, with PSII photochemistry to be adjusted by NPQ in a such way that PSII functionality to be enhanced, but being fully inhibited at the application spot and the adjacent area, after longer exposure (240 min). Hence, the response of tomato PSII to B. cinerea, indicates a hormetic temporal response in terms of “stress defense response” and “toxicity”, expanding the features of hormesis to biotic factors also. The enhanced PSII functionality 30 min after Botrytis application can possible be related with the need of an increased sugar production that is associated with a stronger plant defense potential through the induction of defense genes.

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Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses

Applied Sciences ◽

10.3390/app10155031 ◽

2020 ◽

Vol 10 (15) ◽

pp. 5031 ◽

Cited By ~ 1

Author(s):

Mohammad Yaghoubi Khanghahi ◽

Sabrina Strafella ◽

Carmine Crecchio

Keyword(s):

Chlorophyll Fluorescence ◽

Energy Dissipation ◽

Quantum Yield ◽

Photosystem Ii ◽

Excitation Energy ◽

Durum Wheat ◽

Photochemical Quenching ◽

Plant Growth Promoting Bacteria ◽

Psii Photochemistry ◽

Non Photochemical Quenching

The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy.

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Rapid Hormetic Responses of Photosystem II Photochemistry to Cadmium Exposure

10.20944/preprints202011.0283.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ioannis-Dimosthenis S. Adamakis ◽

Ilektra Sperdouli ◽

Anetta Hanć ◽

Anelia Dobrikova ◽

Emilia Apostolova ◽

...

Keyword(s):

Photosystem Ii ◽

Chloroplast Ultrastructure ◽

Photochemical Quenching ◽

Psii Efficiency ◽

Salvia Sclarea ◽

Whole Plant ◽

Short Period ◽

Psii Photochemistry ◽

Non Photochemical Quenching ◽

Short Time

Five-day exposure of clary sage (Salvia sclarea) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased possible due to translocation barriers. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered, with PSII photochemistry to be regulated by NPQ in such a way that PSII efficiency to be enhanced. However, exposure to a combination of Cd and high light or for longer duration (8 days) to Cd alone, resulted in an inhibition of PSII functionality pointing out towards Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposures and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively.

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State transitions, photosystem stoichiometry adjustment and non-photochemical quenching in cyanobacterial cells acclimated to light absorbed by photosystem I or photosystem II

Photosynthesis Research ◽

10.1007/bf00035446 ◽

1989 ◽

Vol 22 (2) ◽

pp. 157-166 ◽

Cited By ~ 22

Author(s):

John F. Allen ◽

Conrad W. Mullineaux ◽

Christine E. Sanders ◽

Anastasios Melis

Keyword(s):

Photosystem Ii ◽

Photosystem I ◽

State Transitions ◽

Photochemical Quenching ◽

Photosystem Stoichiometry ◽

Non Photochemical Quenching

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Inhibition of non-photochemical quenching increases functional absorption cross-section of photosystem II as excitation from closed reaction centres is transferred to open centres, facilitating earlier light saturation of photosynthetic electron transport

Functional Plant Biology ◽

10.1071/fp20347 ◽

2021 ◽

Author(s):

Charles Barry Osmond ◽

Wah Soon Chow ◽

Sharon A. Robinson

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Cross Section ◽

Absorption Cross Section ◽

Photosynthetic Electron Transport ◽

Photochemical Quenching ◽

Absorption Cross ◽

Light Saturation ◽

Reaction Centres ◽

Non Photochemical Quenching

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Growth under Fluctuating Light Reveals Large Trait Variation in a Panel of Arabidopsis Accessions

Plants ◽

10.3390/plants9030316 ◽

2020 ◽

Vol 9 (3) ◽

pp. 316 ◽

Cited By ~ 1

Author(s):

Elias Kaiser ◽

Dirk Walther ◽

Ute Armbruster

Keyword(s):

Photosystem Ii ◽

Chemical Potential ◽

Genomic Variation ◽

Operating Efficiency ◽

Photochemical Quenching ◽

Low Light ◽

Trait Variation ◽

Light Regimes ◽

Fluctuating Light ◽

Non Photochemical Quenching

The capacity of photoautotrophs to fix carbon depends on the efficiency of the conversion of light energy into chemical potential by photosynthesis. In nature, light input into photosynthesis can change very rapidly and dramatically. To analyze how genetic variation in Arabidopsis thaliana affects photosynthesis and growth under dynamic light conditions, 36 randomly chosen natural accessions were grown under uniform and fluctuating light intensities. After 14 days of growth under uniform or fluctuating light regimes, maximum photosystem II quantum efficiency (Fv/Fm) was determined, photosystem II operating efficiency (ΦPSII) and non-photochemical quenching (NPQ) were measured in low light, and projected leaf area (PLA) as well as the number of visible leaves were estimated. Our data show that ΦPSII and PLA were decreased and NPQ was increased, while Fv/Fm and number of visible leaves were unaffected, in most accessions grown under fluctuating compared to uniform light. There were large changes between accessions for most of these parameters, which, however, were not correlated with genomic variation. Fast growing accessions under uniform light showed the largest growth reductions under fluctuating light, which correlated strongly with a reduction in ΦPSII, suggesting that, under fluctuating light, photosynthesis controls growth and not vice versa.

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