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

Abstract

The reported effects of nitric oxide (NO), a signaling molecule, on the photochemical components of leaves are ambiguous. We examined the changes by a natural NO donor, S-nitrosoglutathione (GSNO). The effect of GSNO on Pisum sativum leaves was studied after a 3-hour exposure in dark, moderate (ML), or high light (HL). The NO levels in GSNO-treated samples were at their maximum under HL, compared to those under ML or dark. Most of the elevated NO was decreased by 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a NO scavenger, confirming the NO increase. Treatment with GSNO caused inhibition of photosynthesis/respiration and restricted electron transport mediated by both photosystem (PS)II and PSI. However, the inhibition by NO-donor of PSII components was stronger than those of PSI. A marked increase in the PSI acceptor side limitation [Y(NA)] and a decrease in PSI donor side limitation [Y(ND)] indicated an upregulation of cyclic electron transport, possibly to balance the damage to PSII by GSNO. We suggest that NO aggravated the HL-induced inhibition of photosynthesis and dark respiration.

State-of-the-Art and Perspectives for Nanomaterials Combined with Nitric Oxide Donors: From Biomedical to Agricultural Applications

“…The use of light can be used to trigger NO release from S -nitrosothiols. Moreover, S -nitrosothiols can undergo reversible S -nitrosylation, releasing NO under physiological conditions. , Examples of RSNOs are S -nitroso- N -acetyl­penicillamine (SNAP) and S -nitroso­glutathione (GSNO). N -Diazeniumdiolates (NONOates) are compounds that contain the [N(O)NO] − functional group, able to release NO both in vitro and in vivo . NONOates are obtained through the reaction between 5 nucleophiles and NO, plus a base for stabilizing the [N(O)NO] − group, leading to the release of 2 mol of NO per mol of NO donor molecule …”

“…The use of light can be used to trigger NO release from S -nitrosothiols. Moreover, S -nitrosothiols can undergo reversible S -nitrosylation, releasing NO under physiological conditions. , Examples of RSNOs are S -nitroso- N -acetyl­penicillamine (SNAP) and S -nitroso­glutathione (GSNO).…”