Hydrogen sulfide regulates photosynthesis of tall fescue under low-light stress

Hydrogen sulfide (H2S) is regarded as gaseous signaling molecule in plant response to various biotic and abiotic stresses. In this study, we investigated potential role of H2S in modulating photosynthesis in low light (LL) stress-induced tall fescue (Festuca arundinacea Schreb.) seedlings. Results demonstrated that LL significantly reduced the plant height, leaf width, tiller number, dry mass, turf quality, chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, maximal quantum yield of PSII photochemistry, photochemical efficiency of PSII, photochemical quenching, electron transport rate, and enzymatic activity of ribulose-1,5-bisphosphate carboxylase. Then, these parameters were found to be considerably alleviated by H2S donor application. Moreover, exogenous application of NaHS decreased the concentration of malondialdehyde, increased activities of peroxidase, superoxide dismutase, ascorbate peroxidase, total soluble sugar, soluble protein, and endogenous concentration of H2S. In addition, these responses could be reversed by treatment with hypotaurine (H2S scavenger) and aminooxy acetic acid (H2S biosynthesis inhibitor). These results suggested that H2S was possibly involved in the regulation of photosynthesis to strengthen LL tolerance by maintaining a high level of photochemical efficiency and improving antioxidant enzyme activities in tall fescue.