Induction of Defense Responses in Cucumber Plants (Cucumis sativus L.) by the Biocontrol Agent Trichoderma harzianum

AUTOR(ES)

Yedidia, I.

FONTE

American Society for Microbiology

RESUMO

The potential of the biocontrol agent Trichoderma harzianum T-203 to trigger plant defense responses was investigated by inoculating roots of cucumber seedlings with Trichoderma in an aseptic, hydroponic system. Trichoderma-treated plants were more developed than nontreated plants throughout the experiment. Electron microscopy of ultrathin sections from Trichoderma-treated roots revealed penetration of Trichoderma into the roots, restricted mainly to the epidermis and outer cortex. Strengthening of the epidermal and cortical cell walls was observed, as was the deposition of newly formed barriers. These typical host reactions were found beyond the sites of potential fungal penetration. Wall appositions contained large amounts of callose and infiltrations of cellulose. The wall-bound chitin in Trichoderma hyphae was preserved, even when the hyphae had undergone substantial disorganization. Biochemical analyses revealed that inoculation with Trichoderma initiated increased peroxidase and chitinase activities within 48 and 72 h, respectively. These results were observed for both the roots and the leaves of treated seedlings, providing evidence that T. harzianum may induce systemic resistance mechanisms in cucumber plants.

Documentos Relacionados

• Defense Responses in Infected and Elicited Cucumber (Cucumis sativus L.) Hypocotyl Segments Exhibiting Acquired Resistance.
• Photochlorophyll Biosynthesis in Cucumber (Cucumis sativus, L.) Cotyledons 1
• Metabolic Implications in the Biochemical Responses to Iron Deficiency in Cucumber (Cucumis sativus L.) Roots.
• Iron-Deficiency Stress Responses in Cucumber (Cucumis sativus L.) Roots (A Possible Role for Ethylene?).
• Electrical Impedance Analysis of Tissue Properties Associated with Ethylene Induction by Electric Currents in Cucumber (Cucumis sativus L.) Fruit.