Combination of the Systemin peptide with the beneficial fungus Trichoderma afroharzianum T22 improves plant defense responses against pests and diseases

Trichoderma spp. are among the most widely used plant beneficial fungi in agriculture. Its interactionwith the plant triggers resistance responses by the activation of Induced Systemic Resistancemediated by Jasmonic acid and Ethylene and/or Systemic Acquired Resistance, which involvesSalicylic acid, with the consequent control of a wide range of plant parasites. However, the benefitthey can confer to plants may be reduced or nullified by environmental conditions or fungalecological fitness. A novel approach to enhance their effectiveness in plant defense is to combinethem with bioactive molecules including plant-derived compounds. Here, we show that planttreatment with Trichoderma afroharzianum (strain T22) and Systemin, a tomato peptide active intriggering plant defense, confers protection against the fungal pathogens Fusarium oxysporum,Botrytis cinerea and the insect pest Tuta absoluta. The observed defensive response was associatedwith an increase of Jasmonic acid and related metabolites and a decrease of salicilic acid.