Transcriptomic and Metabolomic Analyses Reveal That Fusarium sp. Isolate Is Associated with Growth Promotion in Lolium perenne L.

Most previous studies have focused on the pathogenicity of Fusarium species towards crops. In this study, a Fusarium isolate was obtained from healthy Chamelaucium uncinatum plants; its ITS rDNA sequence showed 99% similarity to that of Fusarium napiforme. The fermentation preparation derived from this isolate promoted the growth and biomass accumulation of Lolium perenne L., a high-quality temperate forage grass; following seed treatment with the fermentation broth, the germination rate increased from 61.5% to 82%. In the pot experiment, in which the fermentation preparation was applied by root irrigation, plant height and root length of the host plants increased significantly by 20.0% and 30.6% (p < 0.05) and dry weight increased by 67.6% (p = 0.010), whereas fresh weight showed a non-significant increasing trend (+22.5%, p = 0.136); no disease symptoms were observed. Integrated transcriptomic and metabolomic analyses showed that exposure to the fermentation broth was associated with changes in genes and metabolites related to biomass accumulation. This study identified a candidate fungal isolate for the future development of microbial inoculants for forage crops.