As an important turfgrass and forage grass， perennial ryegrass （Lolium perenne L.） is frequently constrained by high temperature stress during its growth. To explore the effects of PvPCF5 gene functional repression on heat tolerance of perennial ryegrass and its correlation with photosynthesis， wild-type （WT）， PvPCF5 functional repression （PvPCF5-SRDX）， and overexpression （PvPCF5-OX） plants were used as experimental materials and divided into 2 groups with or without heat acclimation， followed by heat stress treatment at 42℃ for different durations. The results showed that under high temperature stress， PvPCF5-SRDX plants exhibited superior physiological performance compared with WT ones， with significantly higher relative water content， and significantly lower electrolyte leakage and malondialdehyde content （P<0.05）. Meanwhile， the photosynthetic pigment contents of PvPCF5-SRDX plants were significantly higher than those of PvPCF5-OX ones （P<0.05）， accompanied by the highest net photosynthetic rate， stomatal conductance and transpiration rate， as well as the lowest intercellular CO₂ concentration. In conclusion， repression of PvPCF5 gene function can effectively improve the photosynthesis of perennial ryegrass and thereby significantly enhance its high temperature tolerance. This study provides a theoretical basis for breeding new heat-tolerant perennial ryegrass varieties.

High temperature  /  Perennial ryegrass  /  PCF5  /  Photosynthesis