Growth-Promoting Effects of VOCs Produced by Trametes hirsuta and Talaromyces pinophilus on Rice

Plant endophytic fungi, which colonize plant tissues and form symbiotic relationships with their hosts, are known for their high diversity and wide distribution. These fungi often influence plant growth and development through the emission of volatile organic compounds (VOCs), whose effects can extend beyond host plants to non-host species. In this study, we isolated two endophytic fungi, Trametes hirsuta RR1 and Talaromyces pinophilus RR2 from healthy rice roots. The VOCs mixtures produced by strains RR1 and RR2 were both able to promote rice growth when these strains were co-cultured with rice seedlings. Specifically, strain RR1 and RR2 increased rice shoot fresh weight by 44.22% and 26.69%, root fresh weight by 58.24% and 41.76%, shoot length by 30.35% and 25.07%, and root length by 29.11% and 4.23%, respectively. They significantly enhanced the contents of chlorophyll a and carotenoids, which increased by 18.61% and 17.04%, and by 18.73% and 31.55%, respectively. Gas chromatography–mass spectrometry (GC-MS) was applied to analyze the VOCs emitted by the two strains. The analysis successfully identified a total of 13 major compounds. Among them, at appropriate concentrations, 1-pentanol, methyl DL-2-methylbutyrate, ethylbenzene, 2-ethyl-p-xylene, ethyl benzoate and dimethyl phthalate, can promote rice growth and alter the contents of photosynthetic pigments and hydrogen peroxide to varying degrees. This study provides an important basis for the in-depth research and development of biofumigants for promoting crop growth.