Previous studies have revealed that calcium (Ca²⁺) and hydrogen peroxide (H₂O₂) are vital secondary messengers in responses to salt stresses in plant. Perennial ryegrass (Lolium perenne L.) is an extensively utilized cool-season grass globally used for forage, turfgrass and soil stabilization. Little is known about the interplay between Ca²⁺ and H₂O₂ signaling in salt-stressed cool-season turfgrass. 

A research team led by Prof. FU Jinmin from Wuhan Botanical Garden investigated the impact of exogenous Ca²⁺ or H₂O₂ on the secondary metabolism and oxidative signaling in perennial ryegrass under salt stress.  

To understand better how Ca²⁺ and H₂O₂ signals are integrated to enhance grass acclimation to stress conditions, plants were separated into six groups with four replicates: 1) nutrient solution (control); 2) 300 mM NaCl+7 mM Ca(NO₃)₂·4H₂O; 3) 300 mM NaCl; 4) H₂O₂; 5) H₂O₂+300 mM NaCl; 6) 300mM NaCl- Ca²⁺ (prepared in half-strength Hoagland’s nutrient solution without Ca ion). 

Exogenous administration with Ca²⁺ alleviated the physiological damage induced by salt tress, as shown by the higher turf quality and lower (electrolyteleakage) EL, (malondialdehyde) MDA and H₂O₂ content, which confirmed that Ca²⁺treatment significantly improved the physiological response of stressed plants. External Ca²⁺ application significantly induced higher K⁺/ Na⁺ ratio in roots at 8 days treatment leaves. However, a higher Ca²⁺/ Mg²⁺ ratio was observed in leaf and root than NaCl-stressed tissues. Ca²⁺ application under salinity inhibited the decrease of enzyme activity, and greater superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activity could be obtained when exogenous application of Ca²⁺ in NaCl solution, which were further confirmed by greatergene transcript abundanceiso enzymes intensity of SOD (3–5), POD (2–5), CAT (1-2), APX (1-5).    

Ca²⁺ and H₂O₂ signals had one common regulation pattern to maintain ROS homeostasis in salt-stressed cool-season turfgrass. In addition, the metabolic profiles revealed that sugars and sugar alcohol accounted for 49.5-88.2% of all metabolites accumulation in all treated leaves and roots. However, the accumulation of these sugars and sugar alcohols displayed opposing trends between Ca²⁺ and H₂O₂ application in salt-stressed plants. Here, H₂O₂/ Ca²⁺-mediated metabolites detected could provide a dataset of common regulatory factors for signaling transduction and salinity acclimation in cool-season turfgrass.