Diversity in plant systemic resistance induced by Trichoderma

• Trichoderma may be biological control agent able to induce systemic resistance in plants.
• Elicitors released by Trichoderma are involved in induction of defense mechanisms.
• Defense induction leads to changes on physiological, biochemical and molecular level.
• Trichoderma-induced resistance may include both ISR and SAR pathways in plants.

Trichoderma species includes many important in agriculture strains, known as effective biological control agents (BCAs). While their capability of mycoparasitism and strong position as antagonists of pathogenic microorganisms are quite well understood, there are still many questions about the process of systemic resistance induced in plants by these fungi. During plant – Trichoderma interaction, numerous elicitors released by the Trichoderma hyphae may induce different types of signals transmitted within the plant e.g. by salicylic acid (SA), jasmonic acid (JA) or reactive oxygen species (ROS), triggering expression of defense proteins. As a result of gene activation, the plant produces enzymes involved in direct supression of pathogens and enhancing the biochemical and structural barriers in plant organism. Depending on the Trichoderma strain, plant species as well as biotic and abiotic conditions, the defensive reactions activated by fungi may oscillate between the two types of systemic resistance: induced systemic resistance (ISR) and systemic acquired resistance (SAR). Different pathways of ISR are investigated both at the biochemical and molecular level, however there are still many issues that need clarification. The main objective of this paper is to present an overview of information about the influence of Trichoderma on the diversity of systemic resistance induction in plants and the possible development of this process.

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