title: Induction of SA-signaling pathway and ethylene biosynthesis in Trichoderma harzianum-treated tomato plants after infection of the root-knot nematode Meloidogyne incognita.
abstract: Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5 days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.
authors.affiliation: Institute of Sustainable Plant Protection (IPSP), National Research Council of Italy (CNR), 70126, Bari, Italy. paola.leonetti@cnr.it.
authors.forename: Paola
authors.identifier: http://orcid.org/0000-0003-2636-3419
authors.initials: P
authors.lastname: Leonetti
authors.affiliation: Institute of Sciences of Food Production (ISPA), National Research Council of Italy (CNR), 70126, Bari, Italy.
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Zonno
authors.affiliation: Institute of Sustainable Plant Protection (IPSP), National Research Council of Italy (CNR), 70126, Bari, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Molinari
authors.affiliation: Institute of Sciences of Food Production (ISPA), National Research Council of Italy (CNR), 70126, Bari, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Altomare
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism; D005030:Ethylenes / Q000096:biosynthesis*; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism / Q000382:microbiology* / Q000469:parasitology*; D054883:Oxylipins / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D014242:Trichoderma / Q000502:physiology*
chemical_list: D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D010940:Plant Proteins; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid
keywords: Ethylene; Hormone-dependent signaling pathways; Jasmonic acid; Plant defense; Root-knot nematodes; Salicylic acid; Trichoderma