Susceptibility toVerticillium longisporumis linked to monoterpene production byTPS23/27 in Arabidopsis

Abstract

SUMMARYThe fungus Verticillium longisporum is a soil-borne plant pathogen of increasing economic importance, and information on plant responses to it is limited. To identify the genes and components involved in the early stages of infection, transcripts in roots of V. longisporum-challenged Arabidopsis Col-0 and the susceptible NON-RACE SPECIFIC DISEASE RESISTANCE 1 (ndr1-1) mutant were compared using ATH1 gene chips. The analysis revealed altered transcript levels of several terpene biosynthesis genes, including the monoterpene synthase TPS23/27. When transgenic 35S:TPS23/27 and TPS23/27-amiRNA plants were monitored the overexpresser line showed enhanced fungal colonization whereas the silenced genotype was indistinguishable from Col-0. Transcript analysis of terpene biosynthesis genes suggested that only the TPS23/27 pathway is affected in the two transgenic genotypes. To confirm changes in monoterpene production, emitted volatiles were determined using solid-phase microextraction and gas chromatography-mass spectrometry. Levels of all identified TPS23/27 monoterpene products were significantly altered in the transgenic plants. A stimulatory effect on conidial germination and hyphal growth of V. longisporum was also seen in co-cultivation with 35S:TPS23/27 plants and upon exposure to 1,8-cineole, the main product of TPS23/27. Methyl jasmonate treatments of myc2-1 and myc2-2 mutants and analysis of TPS23/27:uidA in the myc2-2 background suggested a dependence on jasmonic acid mediated by the transcription factor MYC2. Taken together, our results show that TPS23/27-produced monoterpenes stimulate germination and subsequent invasion of V. longisporum in Arabidopsis roots.

Suppression of abscisic acid biosynthesis at the early infection stage of Verticillium longisporum in oilseed rape (Brassica napus)

“…The fungus probably manipulates ABA signalling in oilseed rape roots in order to prevent a strong JA/ET resistance response and thereby establish a longer lasting compatible interaction with its host (coexistence). This would be in agreement with findings by Roos et al (), who found for Arabidopsis that JA and MYC2 are required for full induction of TPS23/TPS27‐dependent production of monoterpenes, which stimulate germination and enhance V. longisporum invasion. Consequently, myc2‐1 mutants display higher resistance to V. longisporum .…”

Small molecules below‐ground: the role of specialized metabolites in the rhizosphere

“…A similar case was observed in Arabidopsis lines overexpressing the 1,8‐cineole synthases TPS23 and TPS27. Enhanced levels of 1,8 cineole in these transgenic lines in comparison to wild type plants had a stimulatory effect on conidial germination and hyphal growth of the soil‐borne fungal pathogen Verticillium longisporum (Roos et al ., ). Overall, these results exemplify the complexity of dose‐dependent beneficial and harmful interactions mediated by VOCs in the root environment.…”

Large-scale transcriptome comparison of sunflower genes responsive to Verticillium dahliae

“…In recent years, efforts had been made in discovering the molecular mechanisms underlying the interactions between V. dahliae and Arabidopsis, tomato, potato, and cotton plants, and several resistance-related genes and enzymes have been well characterized [6–10]. In the interaction between Arabidopsis thaliana and Verticillium Wilt, Pantelides reported enhanced resistance in etr1-1 [ethylene (ET) receptor mutant] plants, indicating a crucial role for ETR1 in defense against this pathogen, and quantitative polymerase chain reaction analysis suggested that the impaired perception of ET via ETR1 results in increased disease resistance [11].…”