Manganese Repairs the Oxygen-Evolving Complex (OEC) in Maize (Zea mays L.) Damage During Seawater Vulnerability

Abstract

This study was aimed to investigate how exogenous manganese (Mn) would limit damage in the oxygen-evolving complex (OEC) and photosynthetic apparatus of maize seedlings caused during seawater vulnerability. In this study, seawater was applied in 2-week-old maize (Zea mays L.) seedling, and the degree of damage of photosynthetic pigment pool, the OEC, and net electron transport rate were observed. Mn supplement was also added in maize seedlings to limit the damage of the OEC and photosynthetic apparatus caused during salinity. Leaf relative water content (RWC), fresh weight (FW), and photosynthetic pigment pool (chlorophyll a, chlorophyll b, and carotenoids) sharply declined after 7 days of treatment; however, Mn supplement increased these values. Chlorophyll fluorescence induction (OJIP) transients showed low Fv/Fo, an additional K step, enhanced variable fluorescence (VK) and degree of damage to the OEC (WK) during salinity, and indicates damage of OEC at electron donor side of photosystem II (PSII). The OEC intact within PSII was a primary damage center during salinity which inhibited electron transport process that resulted in a huge loss of maximum quantum yield of PSII (Fv/Fm), but a significant recovery in photosynthetic apparatus was observed after exogenous application of manganese. Structural and functional integrity of the photosynthetic apparatus was recovered up to a certain extent after exogenous application of Mn. Findings from this study should help to understand the basic knowledge of photosynthetic apparatus efficiency in response to damage caused by exposure to seawater. Outcomes of this study will be used to mitigate salinity problem with Mn supplement for growth and development of crops.

The effect of nickel phytotoxicity on photosystem II activity and antioxidant enzymes in barley

“…In this study, the decreased value of the parameter area in the leaves of barley clearly confirmed that electron transport rate into PQ pool is reduced by severe nickel stress (Oukarroum et al 2015). In addition, mild, moderate and severe nickel toxicity led to the increased level of the accumulation of the closed reaction centers, as confirmed by higher ΔV/Δ to and lower S M and N values in the leaves of barley (Gupta 2020). Under these conditions, it is clear that PSII reaction centers are already in the closed state (reduced) and small amount of Q A molecules are reduced until Fm value is reached under severe nickel toxicity.…”

Hıyar (Cucumis sativus L.) Bitkilerinde Kadmiyum Toksisitesinin Fotosentetik Aktivite Üzerindeki Etkileri

“…Bu sonuç 1 mM'lık Cd toksisitesinin hıyar yapraklarındaki elektron taşınım reaksiyonlarını belirgin şekilde engellediğini göstermektedir (Meravi ve Prajapati, 2018 (Doğru ve Çakırlar, 2020a(Doğru ve Çakırlar, , 2020b. (Gupta, 2020…”

The oxygen-evolving complex: a super catalyst for life on earth, in response to abiotic stresses

“…In both high and low temperature, Photosystem II complex is the most susceptible part of the photosynthetic apparatus. 19,20,52 The extrinsic proteins viz., PsbO, PsbP, PsbQ, and PsbR disassociates from the OEC complex of PSII. 3 The donor site of the OEC is primary target site to damage under a gradual increase in temperature, causing an appearance of K peak at 0.3 ms on chlorophyll a fluorescence induction curve.…”

“…3 The donor site of the OEC is primary target site to damage under a gradual increase in temperature, causing an appearance of K peak at 0.3 ms on chlorophyll a fluorescence induction curve. 7,20,53,54 Before K-peak discovery, the F O increase was generally used for screening plants for hightemperature sensitivity/resistance. 55,56 PSII repair mechanism inhibited after exposure of low-temperature while no evident for photodamage to PSII.…”

“…15,17,18 Various attempts have made to understand the impact of different abiotic stresses, i.e., high and low temperature, salinity, droughts, highintensity light, on the photosynthetic apparatus of the plants. 3,7,16,19,20 Many workers reviewed the structure and function of PSII under abiotic stresses; however, progress in understanding the structure and function of mysterious super catalyst, i.e., OEC of PSII is faraway. The present review aims to summarise the structural and functional cohesion of the oxygen-evolving complex in response to various abiotic stresses.…”