Reversible changes in structure and function of photosynthetic apparatus of pea (Pisum sativum) leaves under drought stress

Abstract

SUMMARY The effects of drought on photosynthesis have been extensively studied, whereas those on thylakoid organization are limited. We observed a significant decline in gas exchange parameters of pea (Pisum sativum) leaves under progressive drought stress. Chl a fluorescence kinetics revealed the reduction of photochemical efficiency of photosystem (PS)II and PSI. The non‐photochemical quenching (NPQ) and the levels of PSII subunit PSBS increased. Furthermore, the light‐harvesting complexes (LHCs) and some of the PSI and PSII core proteins were disassembled in drought conditions, whereas these complexes were reassociated during recovery. By contrast, the abundance of supercomplexes of PSII‐LHCII and PSII dimer were reduced, whereas LHCII monomers increased following the change in the macro‐organization of thylakoids. The stacks of thylakoids were loosely arranged in drought‐affected plants, which could be attributed to changes in the supercomplexes of thylakoids. Severe drought stress caused a reduction of both LHCI and LHCII and a few reaction center proteins of PSI and PSII, indicating significant disorganization of the photosynthetic machinery. After 7 days of rewatering, plants recovered well, with restored chloroplast thylakoid structure and photosynthetic efficiency. The correlation of structural changes with leaf reactive oxygen species levels indicated that these changes were associated with the production of reactive oxygen species.

Mechanistic Insights on Salicylic Acid Mediated Enhancement of Photosystem II Function in Oregano Seedlings Subjected to Moderate Drought Stress

“…The decreased efficiency of the OEC in H 2 O-sprayed oregano seedlings under MoDS ( Figure 5 ) corresponded with a lower F v /F m ratio ( Figure 1 b). Drought stress limits the availability of H 2 O for water oxidation, affecting the efficiency of the OEC [ 99 , 100 ]. The higher F v /F m ratio of SA-sprayed oregano leaves under MoDS compared to that of the H 2 O-sprayed leaves ( Figure 1 b) was possible due to the amelioration of the oxidative stress, and the decreased quantum yield of non-regulated energy loss (Φ NO ) ( Figure 3 a), which resulted in decreased 1 O 2 formation.…”

Modulation by S-nitrosoglutathione (a natural nitric oxide donor) of photosystem in Pisum sativum leaves, as revealed by chlorophyll fluorescence: Light-dependent aggravation of nitric oxide effects

“…Pre-dark-adapted leaves were treated as required and were kept in darkness for 30 minutes. The PSII and PSI-based Chl fluorescence parameters were measured at 800 and 1000 PAR (µE m -2 s -1 ), respectively (23,24). The PSII parameters were calculated as follows: Maximum photosynthetic efficiency: Fv/Fm = (Fm -Fo)/Fm; Quantum yield of PSII: Y(II) = (Fm′-Ft)/Fm′; Non-regulated energy dissipation: Y(NO) = Ft/FM; Yield of regulatory photo-protective energy dissipation: Y(NPQ) = (Fm′ -Ft/Fm)/Ft; non-photochemical quenching: NPQ, qP, and qL.…”

“…The following PSI parameters were calculated as described (23,24). Maximum photosynthetic efficiency of PSI (Pm); Yield of PSI: Y(I) = (Pm' -P)/Pm; PSI acceptor side limitation: Y(NA) = Pm -Pm')/Pm; and PSI donor side limitation: Y(ND) = P/Pm.…”

Challenges in pea breeding for tolerance to drought: Status and prospects

“…Drought stress, also causes reactive oxygen species (ROS) production in some cell compartments in pea plants, especially in chloroplasts, peroxisomes and mitochondria which can cause lipid peroxidation, membrane damage, protein oxidation and DNA damage (Pandey et al, 2023, Figure 2). Therefore, oxidative stress is the first reaction after the occurrence of abiotic stresses, including drought (Moran et al, 1994, Figure 2).…”

“…The enzymatic mechanism alters the activity of some antioxidant enzymes, namely: superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in pea leaves, that are essential for converting H 2 O 2 to water (H 2 O) and O 2 (Farooq et al, 2021). Maintenance of antioxidant enzyme activity may contribute to drought adaption in pea plants by increasing the capacity of protective mechanisms against oxidative damage (Pandey et al, 2023).…”