Understanding the induction of plant defenses against viruses using biocontrol\udagents is essential for developing new strategies against these pathogens, given the\udineffectiveness of chemical treatments. The ability of Trichoderma harzianum, strain\udT-22 (T22) to control Cucumber mosaic virus (CMV) in Solanum lycopersicum var.\udcerasiforme plants and the changes in the physiology of tomato treated/infected with\udT22/CMV were examined. Plant growth-promoting effects, photosynthetic performance,\udreactive oxygen species scavenging enzymes, and phytohormones were investigated.\udT22 improved tomato growth in terms of plant height and improved photosynthesis, total\udchlorophyll content and plant gas exchange. In contrast, CMV induced a negative effect\udon dry matter accumulation and inhibited the photosynthetic capacity. The analysis\udof plant hormones demonstrated that treating with T22 before or simultaneously to\udCMV infection, led to a systemic resistance by jasmonic acid/ethylene and salicylic\udacid signaling pathways. Conversely, systemic resistance was abscissic acid-dependent\udwhen T22 treatment was administered after the CMV infection. In conclusion, the data\udreported here indicate that the T22-based strategy may be the most effective measure\udagainst CMV.
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