Plant phenomics-assisted selection of Trichoderma spp. strains effective in the biocontrol of tomato soil-borne fungal diseases

The genus Trichoderma is a valuable source of biological control agents: useful means for sustainable crop disease management. Speeding up screening phase in the set-up of new microbial means is crucial to meet needs for managing pathogens. Functional phenomics expressing through objective spectral data the result of the plant genotype's interactions with the environment, can contribute to the performance-based selection. In this study nineteen Trichoderma spp., including strains belonging to the species T. atroviride, T. harzianum, T. longibrachiatum and T. rifaii, were screened for the biocontrol of Fusarium oxysporum f. sp. lycopersici and Sclerotium rolfsii infections on tomato plants, with the help of phenomics measures on infected plants subjected to symptom-reducing effects of the beneficial microbial treatments, alongside the traditional method. Trichoderma spp. isolates showed an antagonistic behavior in plate assays against the two pathogens, while four and five out of total isolates significantly lowered, respectively, wilt and Southern blight symptoms on plants. Detection of the plant phenotype closer to that of the healthy ideotype, defined through the overall computation of biometric and spectral traits acquired by a multispectral dual scan platform, individuated T. harzianum T2 and PB3 as the best performing strains in controlling both tomato pathogens. Leaf area and Normalized Chlorophyll Pigment Ratio Index Average acted as engine vectors for phenotypic clustering with non-infected plants in both systems. Voxel Volume Total, 3D-Leaf area, Green Leaf Index Average, Hue Average, and Surface Angle Average assumed importance under F. oxysporum assay. Specifically, the phenomics assisted procedure contributed to prompt results in the individuation of the best performing Trichoderma strains against F. oxysporum and S. rolfsii.