ABSTRACT
Jasmonate-mediated regulation of VOC emission has been extensively investigated in higher plants, however, only little is known about VOC production and its regulation in ferns. Here, we investigate whether the emission of VOCs from bracken fern Pteridium aquilinum is triggered by herbivory and if so - whether it is regulated by the octadecanoid signaling pathway. Interestingly, feeding of both generalist (Spodoptera littoralis) and specialist (Strongylogaster multifasciata) herbivores as well as application of singular and continuous mechanical wounding of fronds induced only very low levels of VOC emission. In contrast, treatment with jasmonic acid (JA) led to the emission of a blend of VOCs that was mainly comprised of terpenoids. Likewise, treatment with the JA precursor 12-oxo-phytodienoic acid (OPDA) and α-linolenic acid also induced VOC emission, albeit to a lower intesity than the JA treatment. Accumulation of endogenous JA was low in mechanically wounded fronds and these levels were unaffected by the application of oral secretions from both generalist or specialist herbivores. The emission of terpenoids upon JA treatment could be blocked with fosmidomycin and mevinolin, which are inhibitors of the MEP- and MVA pathways, respectively. These results indicate that similar to higher plants, terpenoid VOCs are produced via these pathways in bracken fern and that these pathways are JA-responsive. However, the very low amounts of terpenoids released after herbivory or mechanical damage are in stark contrast to what is known from higher plants. We speculate that S. multifasciata and S. littoralis feeding apparently did not induce the threshold levels of JA required for activating the MEP and MVA pathways and the subsequent volatile emission in bracken fern.
Subject(s)
Cyclopentanes/pharmacology , Herbivory , Hymenoptera/physiology , Oxylipins/pharmacology , Pteridium/metabolism , Pteridium/parasitology , Spodoptera/physiology , Volatile Organic Compounds/metabolism , Animals , Confidence Intervals , Fosfomycin/analogs & derivatives , Fosfomycin/pharmacology , Herbivory/drug effects , Hymenoptera/drug effects , Lovastatin/pharmacology , Oxylipins/metabolism , Pteridium/drug effects , Spodoptera/drug effects , Time FactorsABSTRACT
Herbivore attack by Bolax palliata Burmeister is reported on two sympatric bracken species: Pteridium caudatum (L.) Maxon and P. arachnoideum (Kaulf.). Laboratory and field observations revealed a preference for the last of the two species. Available phytochemical information suggests it could be based on differences in concentration of condensed tannins.
Se reporta la herbivoría de Bolax palliata Burmeister sobre dos especies simpátricas del helecho macho: Pteridium caudatum (L.) Maxon and P. arachnoideum (Kaulf.). Observaciones de laboratorio y campo mostraron preferencia por la última de estas especies. La información fitoquímica disponible sugiere que esta selección podría estar basada en diferencias en la concentración de taninos condensados.
Subject(s)
Animals , Coleoptera/physiology , Food Preferences , Pteridium/parasitology , VenezuelaABSTRACT
Herbivore attack by Bolax palliata Burmeister is reported on two sympatric bracken species: Pteridium caudatum (L.) Maxon and P. arachnoideum (Kaulf.). Laboratory and field observations revealed a preference for the last of the two species. Available phytochemical information suggests it could be based on differences in concentration of condensed tannins.
