title: Carot-4-en-9,10-diol, a conidiation-inducing sesquiterpene diol produced by Trichoderma virens PS1-7 upon exposure to chemical stress from highly active iron chelators.
abstract: To screen biocontrol agents against Burkholderia plantarii, the causative agent of rice seedling blight, we employed catechol, an analog of the virulence factor tropolone, to obtain chemical stress-resistant microorganisms. The fungal isolate PS1-7, identified as a strain of Trichoderma virens, showed the highest resistance to catechol (20 mM) and exhibited efficacy as a biocontrol agent for rice seedling blight. During investigation of metabolic traits of T. virens PS1-7 exposed to catechol, we found a secondary metabolite that was released extracellularly and uniquely accumulated in the culture. The compound induced by chemical stress due to catechol was subsequently isolated and identified as a sesquiterpene diol, carot-4-en-9,10-diol, based on spectroscopic analyses. T. virens PS1-7 produced carot-4-en-9,10-diol as a metabolic response to tropolone at concentrations from 0.05 to 0.2 mM, and the response was enhanced in a dose-dependent manner, similar to its response to catechol at concentrations from 0.1 to 1 mM. Some iron chelators, such as pyrogallol, gallic acid, salicylic acid, and citric acid, at 0.5 mM also showed activation of T. virens PS1-7 production of carot-4-en-9,10-diol. This sesquiterpene diol, formed in response to chemical stress, promoted conidiation of T. virens PS1-7, suggesting that it is involved in an autoregulatory signaling system. In a bioassay of the metabolic and morphological responses of T. virens PS1-7, conidiation in hyphae grown on potato dextrose agar (PDA) plates was either promoted or induced by carot-4-en-9,10-diol. Carot-4-en-9,10-diol can thus be regarded as an autoregulatory signal in T. virens, and our findings demonstrate that intrinsic intracellular signaling regulates conidiation of T. virens.
authors: Hokkaido University, Sapporo, Japan.
authors: Mengcen
authors: M
authors: Wang
authors: Makoto
authors: M
authors: Hashimoto
authors: Yasuyuki
authors: Y
authors: Hashidoko
mesh_terms: D002396:Catechols / Q000378:metabolism; D002614:Chelating Agents / Q000378:metabolism*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012717:Sesquiterpenes / Q000378:metabolism*; D015398:Signal Transduction; D013057:Spectrum Analysis; D013172:Spores, Fungal / Q000254:growth & development*; D013312:Stress, Physiological; D014242:Trichoderma / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D014334:Tropolone / Q000378:metabolism
chemical_list: D002396:Catechols; D002614:Chelating Agents; D004271:DNA, Fungal; D012717:Sesquiterpenes; D014334:Tropolone; D007501:Iron