abstract
Ultraviolet-B (UV-B) radiation plays an important role in plant photomorphogenesis. Whilst the morpho-functional disorders induced by excessive UV irradiation are well-known, it remains unclear how this irradiation modulates the metabolome, and which metabolic shifts improve plants' tolerance to UV-B. In this study, we use an important Mediterranean crop, Olea europaea, to decipher the impacts of enhanced UV-B radiation on the physiological performance and lipophilic metabolite profile. Young olive plants (cv. 'Galega Vulgar') were exposed for five days to UV-B biologically effective doses of 6.5 kJ m(-2) d(-1) and 12.4 kJ d(-1). Cell cycle/ ploidy, photosynthesis and oxidative stress, as well as GC-MS metabolites were assessed. Both UV-B treatments impaired net CO2 assimilation rate, transpiration rate, photosynthetic pigments, and RuBisCO activity, but 12.4 kJ m(-2) d(-1) also decreased the photochemical quenching (qP) and the effective efficiency of PSII (Phi(PSII)). UV-B treatments promoted mono/triperpene pathways, while only 12.4 kJ m(-2) d(-1) increased fatty acids and alkanes, and decreased geranylgeranyl-diphosphate. The interplay between physiology and metabolomics suggests some innate ability of these plants to tolerate moderate UV-B doses (6.5 kJ m(-2) d(-1)). Also their tolerance to higher doses (12.4 kJ m(-2) d(-1)) relies on plants' metabolic adjustments, where the accumulation of specific compounds such as long-chain alkanes, palmitic acid, oleic acid and particularly oleamide (which is described for the first time in olive leaves) play an important protective role. This is the first study demonstrating photosynthetic changes and lipophilic metabolite adjustments in olive leaves under moderate and high UV-B doses.
keywords
PHOTOSYNTHETIC PERFORMANCE; WATER-DEFICIT; OLIVE LEAVES; LEAF; CULTIVARS; RESPONSES; STRESS; MEMBRANE; SATIVA; LIGHT
subject category
Plant Sciences
authors
Dias, MC; Pinto, DCGA; Correia, C; Moutinho-Pereira, J; Oliveira, H; Freitas, H; Silva, AMS; Santos, C
our authors
Helena Oliveira
Post-Doc FellowshipGroups
acknowledgements
We would like to thank University of Aveiro, University of Coimbra and FCT/MEC. This work was financed by FCT/MEC through national funds and the co-funding by the FEDER, within the PT2020 Partnership Agreement, and COMPETE 2010, within the projects UID/BIA/04004/2013 and UID/QUI/00062/2013. The FCT supported Maria Celeste Dias (SFRH/BPD/100865/2014) and Helena Oliveira (SFRH/BPD/111736/2015). For authors integrated in the CITAB research centre, it was further financed by the FEDER/COMPETE/POCI - Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-006958, and by National Funds of FCT-Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.