[Effects of root abscisic acid on Na+ transport and photosystem 2 in Helianthus tuberosus under salt stress]. / ç›èƒè¿«ä¸‹èŠèŠ‹æ ¹ç³»è„±è½é ¸å¯¹é’ ç¦»å­è½¬è¿å’Œå ‰ç³»ç»Ÿâ ¡çš„å½±å“.

The effects of root abscisic acid (ABA) signal on Na+ transport and photosystem 2 (PS2) in Jerusalem artichoke (Helianthus tuberosus) under salt stress (150 mmol·L-1 NaCl) were examined by applying ABA synthesis inhibitor sodium tungstate to roots. Sodium tungstate inhibited ABA synthesis in roots, reduced root Na+ efflux, and increased the efficiency of Na+ transport from roots to leaves under salt stress. Salt stress increased leaf Na+ content and did not affect leaf membrane lipid peroxidation, PS2 reaction center protein and PS2 maximum photochemical efficiency (Fv/Fm ). The inhibition on root ABA synthesis significantly increased leaf Na+ accumulation, aggravated leaf membrane lipid peroxidation, impaired PS2 reaction center protein, decreased Fv/Fm, and induced PS2 photoinhibition. In conclusion, root ABA signal was beneficial to reducing leaf Na+ accumulation and preventing PS2 oxidative damage by inducing root Na+ efflux and inhibiting Na+ transport to the aerial part in H. tuberosus under salt stress.

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

BACKGROUND: Glycine soja is a halophytic soybean native to saline soil in Yellow River Delta, China. Photosystem I (PSI) performance and the interaction between photosystem II (PSII) and PSI remain unclear in Glycine soja under salt stress. This study aimed to explore salt adaptability in Glycine soja in terms of photosystems coordination. RESULTS: Potted Glycine soja was exposed to 300 mM NaCl for 9 days with a cultivated soybean, Glycine max, as control. Under salt stress, the maximal photochemical efficiency of PSII (Fv/Fm) and PSI (△MR/MR0) were significantly decreased with the loss of PSI and PSII reaction center proteins in Glycine max, and greater PSI vulnerability was suggested by earlier decrease in △MR/MR0 than Fv/Fm and depressed PSI oxidation in modulated 820 nm reflection transients. Inversely, PSI stability was defined in Glycine soja, as △MR/MR0 and PSI reaction center protein abundance were not affected by salt stress. Consistently, chloroplast ultrastructure and leaf lipid peroxidation were not affected in Glycine soja under salt stress. Inhibition on electron flow at PSII acceptor side helped protect PSI by restricting electron flow to PSI and seemed as a positive response in Glycine soja due to its rapid recovery after salt stress. Reciprocally, PSI stability aided in preventing PSII photoinhibition, as the simulated feedback inhibition by PSI inactivation induced great decrease in Fv/Fm under salt stress. In contrast, PSI inactivation elevated PSII excitation pressure through inhibition on PSII acceptor side and accelerated PSII photoinhibition in Glycine max, according to the positive and negative correlation of △MR/MR0 with efficiency that an electron moves beyond primary quinone and PSII excitation pressure respectively. CONCLUSION: Therefore, photosystems coordination depending on PSI stability and rapid response of PSII acceptor side contributed to defending salt-induced oxidative stress on photosynthetic apparatus in Glycine soja. Photosystems interaction should be considered as one of the salt adaptable mechanisms in this halophytic soybean.