Endophytic colonisation of perennial ryegrass by Trichoderma atroviride

Content Partner: Lincoln University. Trichoderma spp. are widely used as biocontrol agents and plant growth promoters. Endophytic colonisation of perennial ryegrass (Lolium perenne) by T. atroviride strains was studied in laboratory, greenhouse and field experiments. Four strains of T. atroviride were inoculated into in vitro agar cultures or potting mix with ryegrass seeds for colonisation studies. The strains were also produced as prill or granule formulations for application in the field experiment. Microscopy was used to observe fungal structures in plant tissue segments from pot- or field-grown plants. Segments were also surface sterilised and placed onto Trichoderma selective media. Fungal colonies recovered were verified as T. atroviride by sequencing the tef1 gene. No endophytic colonisation occurred in any non-inoculated plants, and no Trichoderma endophytic colonisation was observed in field-grown plants. However, microscopy revealed fungal hyphae and reproductive structures characteristic of Trichoderma in root and stem sheath tissues of inoculated plants from in vitro cultures and pots. These results were verified by sequencing the tef1 gene. This study has demonstrated endophytic colonisation of ryegrass by T. atroviride strains, which may be related to beneficial effects on plant growth and disease control.