Exogenous Calcium Enhances the Photosystem II Photochemistry Response in Salt Stressed Tall Fescue

Abstract

Calcium enhances turfgrass response to salt stress. However, little is known about PSII photochemical changes when exogenous calcium was applied in salinity-stressed turfgrass. Here, we probe into the rearrangements of PSII electron transport and endogenous ion accumulation in tall fescue (Festuca arundinacea Schreber) treated with exogenous calcium under salt stress. Three-month-old seedlings of genotype “TF133” were subjected to the control (CK), salinity (S), salinity + calcium nitrate (SC), and salinity + ethylene glycol tetraacetic acid (SE). Calcium nitrate and ethylene glycol tetraacetic acid was used as exogenous calcium donor and calcium chelating agent respectively. At the end of a 5-day duration treatment, samples in SC regime had better photochemistry performance on several parameters than salinity only. Such as the Area (equal to the plastoquinone pool size), N (number of QA- redox turnovers until Fm is reached), ψE0, or δRo (Efficiencdy/probability with which a PSII trapped electron is transferred from QA to QB or PSI acceptors), ABS/RC (Absorbed photon flux per RC). All the above suggested that calcium enhanced the electron transfer of PSII (especially beyond QA-) and prevented reaction centers from inactivation in salt-stressed tall fescue. Furthermore, both grass shoot and root tissues generally accumulated more C, N, Ca2+, and K+ in the SC regime than S regime. Interrelated analysis indicated that ψE0, δRo, ABS/RC, C, and N content in shoots was highly correlated to each other and significantly positively related to Ca2+ and K+ content in roots. Besides, high salt increased ATP6E and CAMK2 transcription level in shoot at 1 and 5 day, respectively while exogenous calcium relieved it. In root, CAMK2 level was reduced by Salinity at 5 day and exogenous calcium recovered it. These observations involved in electron transport capacity and ion accumulation assist in understanding better the protective role of exogenous calcium in tall fescue under salt stress.

Physiological mechanisms of exogenous calcium on alleviating salinity-induced stress in rice (Oryza sativa L.)

“…Previous study reported a similar trend of increment in total chlorophyll content by supplementary Ca 2? in Trigonella foenum-graecum (Oprica and Sandu 2014), Festuca arundinacea (Wang et al 2017) and rice (Tahjib-Ul-Arif et al 2018c). The addition of Ca 2?…”

Research on the adaptive mechanism of photosynthetic apparatus under salt stress: New directions to increase crop yield in saline soils

“…In recent decades, exogenous protectants, such as osmoprotectants (mannitol) (Chan, Grumet, & Loescher, ; C. Ma, Ren, Hu, Chen, & Li, ), phytohormones (Brassinosteroids, ABA) (S. Gao, Sun, Li, Shi, & Qi, ; Talaat & Shawky, ; Yue, Zhang, You, Wang, & Zhang, ), signalling molecules (hydrogen sulphide, nitric oxide, γ‐aminobutyric acid) (Deng et al, ; Dong, Jinc, Liu, Xu, & Kong, ; Khoshbakht, Asghari, & Haghighi, ; Y. Wang, Gu, et al, ), polyamines (Spd, Spm, Put) (Khoshbakht, Asghari, & Haghighi, ; Shu et al, ; Yaakoubi, Hamdani, Bekalé, & Carpentier, ), microorganisms (arbuscular mycorrhizal fungi, Bacillus subtilis ) (Han et al, ; Y. Zhang, Gao, Guo, & Hao, ), trace elements (Ca, Si, Se) (Diao et al, ; G. Wang, Bi, et al, ; G. Zhao, Li, Xing, Wang, & Chang, ) and other substances (5‐azacytidine) (Zhong, Xu, & Wang, ) have been found effective in mitigating salt‐induced damages. However, different exogenous substances may be used to enhance plant resistance, but excessive exogenous substances may adversely affect plants.…”

Ultrastructure of Cells and Microanalysis in Malus domestica Borkh. ‘Szampion’ Fruit in Relation to Varied Calcium Foliar Feeding

“…Exogenous Ca 2+ ions play an important role in photosynthesis, as they determine the proper function of photosystem II (PS II-water-plastoquinone oxidoreductase), i.e., the first protein complex located in thylakoid membranes, in the light-dependent reaction of oxygenic photosynthesis, which is responsible for adaptation to stressful conditions [ 10 , 11 ]. Wang et al [ 12 ] showed the protective role of exogenous calcium, suggesting that calcium nitrate enhanced the electron transfer of PSII (especially beyond QA-) and prevented inactivation of reaction centers in salt-stressed tall fescue.…”