Colonization of Arabidopsis roots by Trichoderma atroviride promotes growth and enhances systemic disease resistance through jasmonic acid/ethylene and salicylic acid pathways

Abstract

Trichoderma spp. are common soil fungi used as biocontrol agents due to their capacity to produce antibiotics, induce systemic resistance in plants and parasitize phytopathogenic fungi of major agricultural importance. The present study investigated whether colonization of Arabidopsis thaliana seedlings by Trichoderma atroviride affected plant growth and development. Here it is shown that T. atroviride promotes growth in Arabidopsis. Moreover, T. atroviride produced indole compounds in liquid cultures. These results suggest that indoleacetic acid-related indoles (IAA-related indoles) produced by T. atroviride may have a stimulatory effect on plant growth. In addition, whether colonization of Arabidopsis roots by T. atroviride can induce systemic protection against foliar pathogens was tested. Arabidopsis roots inoculation with T. atroviride provided systemic protection to the leaves inoculated with bacterial and fungal pathogens. To investigate the possible pathway involved in the systemic resistance induced by T. atroviride, the expression profile of salicylic acid, jasmonic acid/ ethylene, oxidative burst and camalexin related genes was assessed in Arabidopsis. T. atroviride induced an overlapped expression of defence-related genes of SA and JA/ET pathways, and of the gene involved in the synthesis of the antimicrobial phytoalexin, camalexin, both locally and systemically. This is the first report where colonization of Arabidopsis roots by T. atroviride induces the expression of SA and JA/ET pathways simultaneously to confer resistance against hemibiotrophic and necrotrophic phytopathogens. The beneficial effects induced by the inoculation of Arabidopsis roots with T. atroviride and the induction of the plant defence system suggest a molecular dialogue between these organisms.

Identifying Beneficial Qualities of Trichoderma parareesei for Plants

“…In accordance with previous studies in which root application of T. harzianum or T. atroviride was able to reduce the leaf lesion area caused by B. cinerea (49,54,55), T. parareesei T6 also triggered ISR against this foliar pathogen.…”

“…Root colonization by Trichoderma triggers a systemic response signaled by JA/ET in a way similar to that described for rhizobacteria (47). Systemic defenses induced by Trichoderma are also signaled by SA (48,49), though they vary depending on the plant genetic background, the interaction time, and the strain and inoculum size (5,50). In the present study, the in vitro assay showed that T. parareesei triggers defense responses against pathogens and salt stress in tomato seedlings.…”

Role of the methylcitrate cycle in growth, antagonism and induction of systemic defence responses in the fungal biocontrol agent Trichoderma atroviride

“…In agreement with published reports (Contreras-Cornejo et al, 2011;Salas-Marina et al, 2011), our results show systemic protection against B. cinerea in WT-colonized Ar. thaliana plants compared with control plants.…”

Trichoderma: A significant fungus for agriculture and environment

“…T. harzianum strain T-22 is the only microbe reported to induce systemic resistance to pathogens in model plants (Contreras-Cornejo et al, 2011;Salas-Marina et al, 2011;Yoshioka et al, 2012) and also in maize indicative of its unique ability (Harman et al 2012). Induced systemic resistance is believed to be one of the most important mechanisms of biocontrol effects of Trichoderma (Harman, 2006).…”