Photosynthetic performance and volatile organic compounds profile in Eucalyptus globulus after UVB radiation

Abstract

Economically important forest species as Eucalyptus globulus face risks associated with climate changes, whose immediate and long-term damages are yet to account. The aim of this study was to decipher the impacts of UV-B radiation on the physiological performance and metabolome profile of leaves of Eucalyptus juvenile plants. For that, three-month-old plants were treated for two days to a total effective radiation of 12kJ m−2. One and 11 d after treatment the samples were collected for photosynthetic analyses. UV-B did not affect the photochemical efficiency or gas exchange, but the total soluble sugars (TSS), starch levels and pigment contents were changed. Changes in TSS and pigment contents persisted in time after the end of exposure. The profile of volatile metabolites (1 and 11 days after stress removal) was analyzed by HS-SPME/GC-IT-MS, and showed abundance of monoterpenes, sesquiterpenes and aldehydes. One day after the stress removal, an increase of aldehydes was observed and a decrease of some monoterpenes and sesquiterpenes. Eleven days after stress removal, some monoterpenes and sesquiterpenes decreased to values closer to those of control. The absence of mortality, and the minor effects observed in photosynthesis suggest a high tolerance profile of this species to the UV-B dose used, which may be justified by changes at the level of primary metabolism (involving sugars) and secondary (e.g. terpenes) observed in response to UV's. The correlations of these changes with potential functional adaptations are discussed here.