Trichoderma asperellum 152-42 enhances growth of perennial ryegrass (Lolium perenne L.) by modulation of plant hormones and carbon-nitrogen metabolism

Abstract

This study elucidates the growth-enhancing mechanisms underlying Trichoderma asperellum 152-42 mediated growth enhancement in perennial ryegrass (Lolium perenne L.) through integrated physiological and transcriptomic analyses. T. asperellum 152-42 inoculation induced significant biomass augmentation, with treated plants exhibiting 26.36 % increased shoot height, 64.96 % roots elongation, 42.02 % shoot fresh weight and 40.65 % shoot dry weight gain versus controls. Notably, root systems displayed sensitivity to fungal symbiosis, correlating with 14.53 % auxin (IAA) elevation and 39.30 % abscisic acid (ABA) reduction. Molecular dissection revealed multilevel regulatory networks: (1) auxin biosynthesis via 2.45-fold transcription factor bHLH128 upregulation and shikimate pathway activation; (2) metabolic restructuring is through expression of gene LOC124653768 encoding phosphoenolpyruvate carboxylase (PEPC) was upregulated by 2.45-fold, and the PEPC enzyme activity increased by 135.60 % enhancing carbon flux. And metabolic restructuring toward increased glycolytic flux through PDC-mediated pyruvate conversion and enhanced anaplerotic carbon fixation via PEPC activity; (3) nitrogen assimilation with 4.1-fold and 2.3-fold upregulation of gene LOC127318565 and gene LOC127305933, respectively, correlating with 23.78 % nitrate reductase (NR) and 8.81 % nitrite reductase (NiR) enzymatic activity increases. The T. asperellum 152-42's growth-promotive effects stem from synergistic hormonal modulation and substrate channeling, where PEPC-derived carbon skeletons fuel NR-mediated nitrogen assimilation. This synergistic integration of hormonal regulation and metabolic network optimization demonstrates microbe-plant partnership.

Our findings advance microbe-plant interaction by delineating the multilevel network through which T. asperellum 152-42 enhances perennial ryegrass productivity. The results offer novel perspectives on microbial-mediated modulation of plant metabolic coordination, with potential applications in sustainable forage cultivation and biofertilizer development.