Root Abscisic Acid Contributes to Defending Photoinibition in Jerusalem Artichoke (Helianthus tuberosus L.) under Salt Stress

Abstract

The aim of the study was to examine the role of root abscisic acid (ABA) in protecting photosystems and photosynthesis in Jerusalem artichoke against salt stress. Potted plants were pretreated by a specific ABA synthesis inhibitor sodium tungstate and then subjected to salt stress (150 mM NaCl). Tungstate did not directly affect root ABA content and photosynthetic parameters, whereas it inhibited root ABA accumulation and induced a greater decrease in photosynthetic rate under salt stress. The maximal photochemical efficiency of PSII (Fv/Fm) significantly declined in tungstate-pretreated plants under salt stress, suggesting photosystem II (PSII) photoinhibition appeared. PSII photoinhibition did not prevent PSI photoinhibition by restricting electron donation, as the maximal photochemical efficiency of PSI (ΔMR/MR0) was lowered. In line with photoinhibition, elevated H2O2 concentration and lipid peroxidation corroborated salt-induced oxidative stress in tungstate-pretreated plants. Less decrease in ΔMR/MR0 and Fv/Fm indicated that PSII and PSI in non-pretreated plants could maintain better performance than tungstate-pretreated plants under salt stress. Consistently, greater reduction in PSII and PSI reaction center protein abundance confirmed the elevated vulnerability of photosystems to salt stress in tungstate-pretreated plants. Overall, the root ABA signal participated in defending the photosystem’s photoinhibition and protecting photosynthesis in Jerusalem artichoke under salt stress.

Salt adaptability in a halophytic soybean (Glycine soja) involves photosystems coordination

“…6). Photosystems photoinhibition usually arises in parallel with elevated leaf lipid peroxidation under environmental stresses, and notably, the negative correlation of ROS production with PSI and PSII photochemical capacity under salt stress has been evidenced [18,25,28,44]. As a result, unchanged lipid peroxidation and H 2 O 2 concentration implied that photosystems were less endangered by salt-induced oxidative stress in Glycine soja than Glycine max.…”

“…Pn and g s were simultaneously recorded. Modulated chlorophyll fluorescence was also recorded for calculating ETR and 1-qP according to previous studies [25,55].…”

“…Leaf tissues (0.5 g) were ground under liquid nitrogen and homogenized in 5 mL 0.1% TCA. The homogenate was centrifuged at 10000×g and 4°C for 10 min to collect the supernatant for measuring MDA and H 2 O 2 contents [25]. Leaves were vacuum-infiltrated with 0.1 mg ml − 1 3, 3-diaminobenzidine in 50 mM trisacetate solution (pH, 3.8) and incubated at room temperature in the dark for 24 h. Thereafter, the leaves were decolorized by immersion in boiling ethanol (80%) for 10 min and photographed [59].…”

“…Up to now, very limited attention has been paid to photosystem I (PSI) under salt stress, let alone the interaction between PSII and PSI [16]. In our recent studies, PSI was proved to be a crucial photoinhibition site in some glycophytic crops under salt stress [18,25,26].…”

“…PSI photoinhibition can intensify PSII excitation pressure through feedback inhibition on electron transport and aggravate PSII photoinhibition [27,28]. Accordingly, PSI inactivation has been found in susceptible plant species or cultivars with weak adaptability to abiotic stresses [18,25,28]. In contrast, PSII photoinhibition which restricts electron donation to PSI can help to prevent PSI photoinhibition by reducing ROS generation through Mehler reaction at PSI acceptor side [29][30][31][32][33].…”