(-)-Catechin mediates both allelopathy and phosphorus mobilization via leaf litter and root exudates in low-phosphorus granite soils

In acidic granite soils, phosphorus (P) deficiency limits plant growth. It remains unclear whether specific metabolites can simultaneously mediate nutrient mobilization and allelopathy. Triadica sebifera (Euphorbiaceae) thrives in granite soils. This study investigates whether catechin released by T. sebifera exerts dual ecological functions, characterizes its environmental dynamics, and examines its temperature-dependent interactions. Metabolomic analyses were conducted on root exudates of T. sebifera under low-P conditions, field litter, and soils. The allelopathic effect of catechin was assessed by treating Chrysanthemum seticuspe seeds. Its interaction with heat stress was investigated, and transcriptomic analysis was used to determine the combined effect on the radicle and hypocotyl development of the recipient plant. The influence of catechin on P mobilization in acidic soil was also evaluated. Catechin was detected in both root exudates and litter. Its concentration in soil decreased over time. Catechin exerted a concentration-dependent inhibitory effect on recipient plants, which was enhanced under elevated temperatures. However, this enhancement did not reflect an increase in its intrinsic allelopathy. Transcriptomic analysis revealed that elevated temperature increased oxidative damage and stress responses in different tissues, thereby enhancing plant sensitivity to the allelopathic effects of catechin. Moreover, catechin significantly mobilized available P in acidic soil. Catechin released through root exudation and litter functions as a dual ecological mediator, integrating P mobilization and allelopathy. This secondary metabolite-mediated mechanism may enhance nutrient acquisition and ecological competitiveness of T. sebifera in granite-derived ecosystems. Furthermore, elevated temperature may amplify this ecological advantage by affecting recipient responses.