Achotegui-Castells A., Della Rocca G., Llusià J., Danti R., Barberini S., Bouneb M., Simoni S., Michelozzi M., Peñuelas J. (2016) Terpene arms race in the Seiridium cardinale - Cupressus sempervirens pathosystem. Scientific Reports. 6: 0-0.EnllaçDoi: 10.1038/srep18954
The canker-causing fungus Seiridium cardinale is the major threat to Cupressus sempervirens worldwide. We investigated the production of terpenes by canker-resistant and susceptible cypresses inoculated with S. cardinale, the effect of these terpenes on fungal growth, and the defensive biotransformation of the terpenes conducted by the fungus. All infected trees produced de novo terpenes and strongly induced terpenic responses, but the responses were stronger in the canker-resistant than the susceptible trees. In vitro tests for the inhibition of fungal growth indicated that the terpene concentrations of resistant trees were more inhibitory than those of susceptible trees. The highly induced and de novo terpenes exhibited substantial inhibition (more than a fungicide reference) and had a high concentration-dependent inhibition, whereas the most abundant terpenes had a low concentration-dependent inhibition. S. cardinale biotransformed three terpenes and was capable of detoxifying them even outside the fungal mycelium, in its immediate surrounding environment. Our results thus indicated that terpenes were key defences efficiently used by C. sempervirens, but also that S. cardinale is ready for the battle.
Achotegui-Castells A., Danti R., Llusia J., Rocca G.D., Barberini S., Penuelas J. (2015) Strong Induction of Minor Terpenes in Italian Cypress, Cupressus sempervirens, in Response to Infection by the Fungus Seiridium cardinale. Journal of Chemical Ecology. : 0-0.EnllaçDoi: 10.1007/s10886-015-0554-1
Seiridium cardinale, the main fungal pathogen responsible for cypress bark canker, is the largest threat to cypresses worldwide. The terpene response of canker-resistant clones of Italian cypress, Cupressus sempervirens, to two differently aggressive isolates of S. cardinale was studied. Phloem terpene concentrations, foliar terpene concentrations, as well as foliar terpene emission rates were analyzed 1, 10, 30, and 90 days after artificial inoculation with fungal isolates. The phloem surrounding the inoculation point exhibited de novo production of four oxygenated monoterpenes and two unidentified terpenes. The concentrations of several constitutive mono- and diterpenes increased strongly (especially α-thujene, sabinene, terpinolene, terpinen-4-ol, oxygenated monoterpenes, manool, and two unidentified diterpenes) as the infection progressed. The proportion of minor terpenes in the infected cypresses increased markedly from the first day after inoculation (from 10 % in the control to 30–50 % in the infected treatments). Foliar concentrations showed no clear trend, but emission rates peaked at day 10 in infected trees, with higher δ-3-carene (15-fold) and total monoterpene (10-fold) emissions than the control. No substantial differences were found among cypresses infected by the two fungal isolates. These results suggest that cypresses activate several direct and indirect chemical defense mechanisms after infection by S. cardinale. © 2015 Springer Science+Business Media New York
Achotegui-Castells A., Llusia J., Hodar J.A., Penuelas J. (2013) Needle terpene concentrations and emissions of two coexisting subspecies of Scots pine attacked by the pine processionary moth (Thaumetopoea pityocampa). Acta Physiologiae Plantarum. 35: 3047-3058.EnllaçDoi: 10.1007/s11738-013-1337-3
Mediterranean pine forests are often attacked by caterpillars of Thaumetopoea pityocampa (Lep., Thaumetopoidae), one of the most important defoliators in the Mediterranean region causing large economic losses and ecological effects. The needle terpene concentrations and emissions may play a key role in the defense of pines. We studied two subspecies of Pinus sylvestris, nevadensis (an endemic and relict subspecies) and iberica, with different levels of caterpillar attack in Sierra Nevada mountains (Spain). GC-MS analyses showed large total concentrations of terpenes (6 to 39 mg g-1 of dry weight) in the needles of both subspecies under field conditions. Concentrations were 25 % higher in "Non-Attacked Trees" (NATs) of the iberica than in the nevadensis subspecies. The branches of NATs had terpene concentrations 20 % higher than those of "Attacked Branches of attacked trees" (ABs). Within attacked trees, the "Non-Attacked Branches" (NABs) also had terpene concentrations 20 % higher than those of ABs. Mainly α-pinene and germacrene D had higher concentrations in NATs and NABs than in ABs. Some terpenes had higher concentrations in NABs than in NATs, indicating possible systemic reactions. In subsp. nevadensis, the percentage of monoterpenes relative to total terpenes was higher in ABs than in other attack states. The rates of emission in nevadensis (standardized to 30 °C) were ca. three times higher in ABs than in NABs and NATs. These results suggest that the lower terpene concentrations and high percentages of monoterpenes in ABs were produced by a combination of emission losses and terpene induction in response to herbivorous attack. © 2013 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Carnicer J, Rico L, Garbulsky M, Coll M, Díaz de Quijano M, Seco R, Rivas-Ubach A, Kefauver S, Barbeta A, Achoategui A, Mejía-Chang M, Gallardo A, Farre G, Fernández M, Terradas J (2012) Ecosystemic and biospheric interactions with carbon cycle. In Carbon dioxide budget: processes and tendencies symposium. Universitat Politècnica de Catalunya, May 23-25.
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