9 research outputs found
Histidine kinase two-component response regulators Ssk1, Skn7 and Rim15 differentially control growth, developmental and volatile organic compounds emissions as stress responses in Trichoderma atroviride
The Skn7, Ssk1 and Rim15 proteins are response regulators involved in osmotic, oxidative and nutritional stress in fungi. In order to verify the involvement of these genes in Trichoderma atroviride IMI206040’s growth, conidiation, direct antagonism against plant pathogens (Rhizoctonia solani and Sclerotinia sclerotiorum), production of volatile organic compounds (VOCs) with fungistatic effect, and interaction with plants (growth promotion), single mutants were generated, and the phenotypic patterns were analysed in comparison to the wild-type (wt) strain. The mutants were submitted to osmotic, oxidative, membrane and cell wall stress conditions in vitro. The Δskn7 and Δrim15 mutants did not show either significant differences at morphological level, or marked decreases in mycelial growth and conidiation in relation to wt, whereas Δssk1 had altered phenotypes in most conditions tested. The plant-growth promotion of Arabidopsis thaliana seedlings induced by VOCs was not quantitatively modified by any of the mutants in relation to the wt strain, although possible differences in secondary root hairs was noticed for Δrim15. The fungistatic activity was significantly altered for Δssk1 and Δrim15. Overall, the Δssk1 strain showed remarkable morphological differences, with decrease in mycelial growth and conidiation, being also affected in the antagonistic capacity against plant pathogens. The impacts demonstrated by the deletion of ssk1 suggest this gene has a relevant participation in the signalling response to different stresses in T. atroviride and in the interactive metabolism with phytopathogens and plants. On the other hand, unlike other fungal models, Skn7 did not appear to have a critical participation in the above-mentioned processes; Rim15 seemed to confirm its involvement in modulating cellular responses to nutritional status, although with a possible cross-talk with other cellular processes. Our results suggest that Ssk1 likely plays a key regulatory role, not only in basic metabolisms of T. atroviride, but also in biocontrol-related characteristics
An injury-response mechanism conserved across kingdoms determines entry of the fungus Trichoderma atroviride into development
A conserved injury-defense mechanism is present in plants and
animals, in which the production of reactive oxygen species (ROS)
and lipid metabolism are essential to the response. Here, we describe
that in the filamentous fungus Trichoderma atroviride, injury results
in the formation of asexual reproduction structures restricted to
regenerating cells. High-throughput RNA-seq analyses of the response
to injury in T. atroviride suggested an oxidative response
and activation of calcium-signaling pathways, as well as the participation
of lipid metabolism, in this phenomenon. Gene-replacement
experiments demonstrated that injury triggers NADPH oxidase
(Nox)–dependent ROS production and that Nox1 and NoxR are essential
for asexual development in response to damage. We further
provide evidence of Hâ‚‚Oâ‚‚ and oxylipin production that, as in plants
and animals, may act as signal molecules in response to injury in
fungi, suggesting that the three kingdoms share a conserved
defense-response mechanism