• fusarium ear rot
• Fusarium verticillioides
• maize
• plant defence response
• roots endophytism
• Trichoderma gamsii

Fusarium verticillioides is one of the major pathogens threatening maize, a worldwide important crop. Besides reducing its yield and quality, the pathogen produces fumonisins, mycotoxins harmful to humans and animals. Among environment-friendly tools, the use of biocontrol agents (BCAs) is a promising approach to reduce F. verticillioides-caused maize disease. Within the fungal genus Trichoderma, several isolates are studied for their biocontrol abilities. Trichoderma gamsii T6085 has been successfully studied as a BCA against Fusarium head blight in wheat. In view of its use as BCA of F. verticillioides on maize, the present thesis aimed to assess the ability of T6085 to endophytically colonize maize roots and to analyze the modulation of defense-related (DR) genes in the host plant.
To test T6085 endophytic colonization of maize roots, seeds (Mergoscia - zu40) were surface sterilized, plated on P190 and, after 3 days, inoculated with T6085 mycelium. Uninoculated roots were used as control. After 5 days, roots were surface sterilized and plated on new P190 plates to check percentage of roots colonized by T6085.
For molecular analysis of the cross-talk occurring between roots and T6085, RNA was extracted from inoculated and control roots and from T6085 mycelium and used for qPCR. Primers for maize DR (hpl, chit2, lox10) and housekeeping genes were designed and validated. Additionally, relative expression of T6085 thy, tri5 and epol genes was investigated. Data were submitted to statistical analysis (ANOVA) to assess gene modulation during T6085-root interaction.
Results showed a successful endophytic colonization of maize roots by T6085 and provided insights into the molecular interactions between maize and the candidate BCA. qPCR on maize genes showed a significant up-regulation of that encoding for chitinase 2 (chit2). From T6085 perspective, our results showed a significant up-regulation of the tri5 gene (encoding for a trichodiene synthase) during fungal-plant interaction.
Results herewith obtained, together with previous information on the antagonistic ability of T6085 vs F. verticillioides, highlight the potential of T. gamsii T6085 as a beneficial endophyte for maize to improve plant health. Further in vivo tests are needed to fully appreciate this isolate as BCA of F. verticillioides-caused maize disease.