Response of linear and cyclic electron flux to moderate high temperature and high light stress in tomato

Self Cite

110

Low light (LL) is one of the main limiting factors that negatively affect tomato growth and yield. Techniques of chemical regulation are effective horticultural methods to improve stress resistance. Strigolactones (SLs), newly discovered phytohormones, are considered as important regulators of physiological responses. We investigated the effects of foliage spray of GR24, a synthesized SLs, on tomato seedlings grown under LL stress conditions. The results showed that application of GR24 effectively mitigated the inhibition of plant growth and increased the fresh and dry weight of tomato plants under LL. Additionally, GR24 also increased the chlorophyll content (Chl a and Chl b ), the net photosynthetic rate (Pn), the photochemical efficiency of photosystem (PS) II (Fv/Fm), and the effective quantum yield of PSII and I [Y(II) and Y(I)], but decreased the excitation pressure of PSII (1-qP), the non-regulatory quantum yield of energy dissipation [Y(NO)] and the donor side limitation of PSI [Y(ND)] under LL. Moreover, application of GR24 to LL-stressed tomato leaves increased the electron transport rate of PSII and PSI [ETR(II) and ETR(I)], the ratio of the quantum yield of cyclic electron flow (CEF) to Y(II) [Y(CEF)/Y(II)], the oxidized plastoquinone (PQ) pool size and the non-photochemical quenching. Besides, GR24 application increased the activity and gene expression of antioxidant enzymes, but it reduced malonaldehyde (MDA) and hydrogen peroxide (H 2 O 2 ) content in LL-stressed plants. These results suggest that exogenous application of GR24 enhances plant tolerance to LL by promoting plant utilization of light energy to alleviate the photosystem injuries induced by excess light energy and ROS, and enhancing photosynthesis efficiency to improve plant growth.

Section: Methodsmentioning

confidence: 99%

Improving Plant Growth and Alleviating Photosynthetic Inhibition and Oxidative Stress From Low-Light Stress With Exogenous GR24 in Tomato (Solanum lycopersicum L.) Seedlings

et al. 2019

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110

“…As plants are sessile, they have to face all these thermo-challenges in their natural ecosystems. While effect of extreme high temperatures on plant growth can be recognized by visible sign and yield reduction, sub high temperatures (SHT), which are just above physiological optimum, can cause massive metabolic changes without showing visible symptoms ( Ahammed et al, 2016 ; Lu et al, 2017 ; Ohama et al, 2017 ). These responses are cumulative that comprise physiological, metabolic and transcriptional reprogramming ( Liu Z.W.…”

Section: Introductionmentioning

confidence: 99%

Brassinosteroids Attenuate Moderate High Temperature-Caused Decline in Tea Quality by Enhancing Theanine Biosynthesis in Camellia sinensis L.

Wei

Ahammed

et al. 2018

Temperature is a major environmental signal that governs plant growth and development. A moderately high ambient temperature alters plant metabolism without significant induction of heat–stress responses. Despite ancillary reports on the negative effect of warmer climate on tea quality, information on specific effect of sub high temperature (SHT) on theanine accumulation is scanty. L-Theanine is the most abundant free amino acid in tea (Camellia sinensis L.) leaves that contributes to the unique umami flavor of green tea infusion. Tea harvested in warmer months lacks distinctive umami taste due to low theanine content. In this study, we showed that SHT (35°C) gradually decreased theanine concentration over time, which was closely associated with the SHT-induced suppression in theanine biosynthetic genes. 24-epibrassinolide (BR), a bioactive brassinosteroids, attenuated the SHT-induced reduction in theanine concentration by upregulating the transcript levels of theanine biosynthetic genes, such as ARGININE DECARBOXYLASE (CsADC), GLUTAMINE SYNTHETASE (CsGS), GLUTAMATE SYNTHASE (CsGOGAT) and THEANINE SYNTHASE (CsTS). Furthermore, time-course analysis of the activity of theanine biosynthetic enzyme reveals that BR-induced regulation of GS and GOGAT activity plays essential role in maintaining theanine content in tea leaves under SHT, which is consistent with the central position of GOGAT in theanine biosynthetic pathway. Therefore, it is convincing to propose that exogenous BR treatment can be advocated to improve summer tea quality by enhancing in vivo accumulation of theanine. However, a future challenge is to use this information on the role of BR in theanine biosynthesis and thermotolerance to further understand how BR may be tuned to benefit plant fitness for enhancing tea quality.

“…Plants also effectively dissipated over-excitation by the transition of LEF to CEF, which relieves the excitation pressure in photosystems and diminishes ROS generation (Tu et al, 2016;Podgórska et al, 2020). This was confirmed in Solanum lycopersicum grown under high temperature and high light treated with LEF inhibitor: 3-(3,4dichlorophenyl)-1,1-dimethyl urea (DCMU) and CEF inhibitor: methyl viologen (MV) (Lu et al, 2017). CEF (CEF-PSI) and moderate photoinhibition of PSII are two main protecting mechanisms of PSI photoinhibition (Zhang et al, 2014;Huang et al, 2016a).…”

Section: Introductionmentioning

confidence: 78%

“…The over-reduction of PSI acceptor side and production of hydroxide at PSI acceptor side are regarded as two main causes of PSI photoinhibition ( Munekage et al, 2002 ; Tikkanen et al, 2014 ). Water–water cycle induces the production of hydroxyl peroxide at PSI acceptor side in C. sativus , S. oleracea , A. thaliana , and S. lycopersicum under chilling temperature or high light, which further leads to PSI photoinhibition ( Sonoike, 1996 ; Zhang and Scheller, 2004 ; Lu et al, 2017 ). Y(NA) decreased with the increase of N levels, but Y(ND) was significantly higher than Y(NA), and MV-treated plants showed higher Y(NA) ( Figure 7 ).…”

Section: Discussionmentioning

confidence: 99%

Responses of Linear and Cyclic Electron Flow to Nitrogen Stress in an N-Sensitive Species Panax notoginseng

Zhang

Shuang

et al. 2022

Nitrogen (N) is a primary factor limiting leaf photosynthesis. However, the mechanism of N-stress-driven photoinhibition of the photosystem I (PSI) and photosystem II (PSII) is still unclear in the N-sensitive species such as Panax notoginseng, and thus the role of electron transport in PSII and PSI photoinhibition needs to be further understood. We comparatively analyzed photosystem activity, photosynthetic rate, excitation energy distribution, electron transport, OJIP kinetic curve, P700 dark reduction, and antioxidant enzyme activities in low N (LN), moderate N (MN), and high N (HN) leaves treated with linear electron flow (LEF) inhibitor [3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU)] and cyclic electron flow (CEF) inhibitor (methyl viologen, MV). The results showed that the increased application of N fertilizer significantly enhance leaf N contents and specific leaf N (SLN). Net photosynthetic rate (Pn) was lower in HN and LN plants than in MN ones. Maximum photochemistry efficiency of PSII (Fv/Fm), maximum photo-oxidation P700+ (Pm), electron transport rate of PSI (ETRI), electron transport rate of PSII (ETRII), and plastoquinone (PQ) pool size were lower in the LN plants. More importantly, K phase and CEF were higher in the LN plants. Additionally, there was not a significant difference in the activity of antioxidant enzyme between the MV- and H2O-treated plants. The results obtained suggest that the lower LEF leads to the hindrance of the formation of ΔpH and ATP in LN plants, thereby damaging the donor side of the PSII oxygen-evolving complex (OEC). The over-reduction of PSI acceptor side is the main cause of PSI photoinhibition under LN condition. Higher CEF and antioxidant enzyme activity not only protected PSI from photodamage but also slowed down the damage rate of PSII in P. notoginseng grown under LN.