Light and mycelial injury influences the volatile and non-volatile metabolites and the biocontrol properties of Trichoderma atroviride

Abstract

Trichoderma spp. are common inhabitants of the rhizosphere, which produce volatile organic compounds (VOCs) and diffusible molecules such as indole-3-acetic acid (IAA) for the communication with plants. Here, we report that fungal VOCs and IAA production, as well as growth and sporulation change upon mechanical damage and compromise its biocontrol properties. Mycelium injury in combination with photoperiod conditions triggered conidiogenesis, stimulated IAA secretion, and enhanced the emission of 2-heptanone, 2-nonanone, and 1-octen-3-ol, but diminished the emission of 6-pentyl-2H-pyran-2-one (6-PP). The opposite effects were observed under darkness, where the content of 1-octen-3-ol decreased while the abundance of 6-PP increased. Arabidopsis thaliana growth promotion through fungal VOCs and diffusible compounds was sustained upon injury while in-vitro confrontation experiments showed the influence of light in the performance of the WT strain against the necrotrophic fungus Botrytis cinerea likely via 6-PP production, which inhibited B. cinerea growth. These results show that the biochemical and ecological attributes of T. atroviride are modulated by the fungal integrity and light signaling.