Trichoderma-Plant Root Colonization: Escaping Early Plant Defense Responses and Activation of the Antioxidant Machinery for Saline Stress Tolerance

Abstract

Trichoderma spp. are versatile opportunistic plant symbionts which can colonize the apoplast of plant roots. Microarrays analysis of Arabidopsis thaliana roots inoculated with Trichoderma asperelloides T203, coupled with qPCR analysis of 137 stress responsive genes and transcription factors, revealed wide gene transcript reprogramming, proceeded by a transient repression of the plant immune responses supposedly to allow root colonization. Enhancement in the expression of WRKY18 and WRKY40, which stimulate JA-signaling via suppression of JAZ repressors and negatively regulate the expression of the defense genes FMO1, PAD3 and CYP71A13, was detected in Arabidopsis roots upon Trichoderma colonization. Reduced root colonization was observed in the wrky18/wrky40 double mutant line, while partial phenotypic complementation was achieved by over-expressing WRKY40 in the wrky18 wrky40 background. On the other hand increased colonization rate was found in roots of the FMO1 knockout mutant. Trichoderma spp. stimulate plant growth and resistance to a wide range of adverse environmental conditions. Arabidopsis and cucumber (Cucumis sativus L.) plants treated with Trichoderma prior to salt stress imposition show significantly improved seed germination. In addition, Trichoderma treatment affects the expression of several genes related to osmo-protection and general oxidative stress in roots of both plants. The MDAR gene coding for monodehydroascorbate reductase is significantly up-regulated and, accordingly, the pool of reduced ascorbic acid was found to be increased in Trichoderma treated plants. 1-Aminocyclopropane-1-carboxylate (ACC)-deaminase silenced Trichoderma mutants were less effective in providing tolerance to salt stress, suggesting that Trichoderma, similarly to ACC deaminase producing bacteria, can ameliorate plant growth under conditions of abiotic stress, by lowering ameliorating increases in ethylene levels as well as promoting an elevated antioxidative capacity.

Identifying Beneficial Qualities of Trichoderma parareesei for Plants

“…Tomato seed treatment with T. harzianum confers protection against oxidative damage, alleviating the biotic, abiotic, and physiological stresses of germinating seeds and seedlings (56). We had observed the upregulation of several genes related to responses against abiotic stresses in Arabidopsis after 24 h of incubation in the presence of T. harzianum (12), and a recent study reported that Trichoderma can induce the expression of APX1 in salt-stressed Arabidopsis plants (57). The slight APX1 upregulation observed in in vitro assays and the absence of significant expression changes in the time course study (data not shown) could be due to the absence of salt-stressed plants in these assays.…”

A cultured endophyte community is associated with the plant Clerodendrum inerme and antifungal activity

“…The genus Trichoderma includes opportunistic plant symbionts that can colonize the apoplast of the plant roots (Brotman et al, 2013). The counter inhibition of Trichoderma against Fusarium has been observed in vitro, and Trichoderma spp may be used as ideal biocontrol agents (Dube et al, 2007;Poornima, 2011).…”

Trichoderma-based Products and their Widespread Use in Agriculture

“…However, more and more evidence has been accumulated that demonstrates that these benefits and effects from Trichoderma applications are much more extensive. Trichoderma is capable of systemically activating plant defence mechanisms including priming, that anticipate pathogen attack [5,57,64,[66][67][68][69]. The reaction of the plant to the BCA is similar to the ISR elicited by rhizobacteria [70][71][72][73][74][75][76].…”