Physiological Responses of a Centipedegrass Mutant to Chilling Stress

Abstract

Physiological responses to chilling in γ‐ray‐induced mutant 22‐3 compared with two wild‐type lines (W1 and W2) with yellow‐stemmed stolons from the cultivar Common were analyzed to understand the chilling tolerance mechanism of centipedegrass [ Eremochloa ophiuroides (Munro) Hack.]. The mutant 22‐3 showed an elevated chilling tolerance, with lower ion leakage and higher chlorophyll content after chilling treatment than the wild‐type plants. The maximum photochemical efficiency, quantum efficiency of photosystem II photochemistry, photochemical quenching efficiency, and net photosynthetic rate decreased after chilling treatment but were less affected in 22‐3 than in the wild‐type plants. Consistently higher levels of maximum net photosynthetic rate, apparent quantum yield, carboxylation efficiency, and light saturation point and lower levels of the CO 2 compensation point and light compensation point were observed in 22‐3 than in the wild‐type plants after chilling treatment. Antioxidant enzyme activities and polyamines (PAs) including putrescine (Put), spermidine (Spd), and spermine (Spm) remained higher in 22‐3 relative to the wild‐type plants during chilling stress. Activities of superoxide dismutase, ascorbate‐peroxidase (APX), catalase (CAT), and glutathione reductase (GR) were highly correlated with Put and Spm, while APX, CAT, and GR were highly correlated with Spd. The results suggest that higher levels of PAs and antioxidants are associated with the elevated chilling tolerance in 22‐3 and improve protection of photosynthesis against chilling‐induced oxidative damage. We propose that manipulation of the biosynthesis of PAs could be valuable in centipedegrass breeding for increased chilling tolerance.