abstract
Extreme climate change events, such as long periods of drought and heat waves, are predicted to increase throughout this century. Pinus species are important economic resources. However, it remains unknown the vulnerability of most species to climate change-related stresses. We aimed to compare the performance reconfiguration of two resin/timber important species [Pinus elliottii var. elliottii (PE) and the hybrid Pinus elliottii var. elliottii x Pinus caribaea var. hondurensis (PE x PCH)] to face combined stress of drought+heat. Young PE and PE x PCH plants were grown at optimal conditions, then exposed to water deficit for 5 days, and in the last day of water deficit, plants were additionally exposed to a heat shock. The physiological responses, antioxidant capacity and oxidative stress were evaluated immediately and 5 days (recovery) after drought+heat treatment. Under control conditions, the hybrid displayed higher photosynthetic and biochemical performance (e.g. higher net CO2 assimilation rate, transpiration rate, photosynthetic pigments and anthocyanins levels, carbohydrates and antioxidant enzyme activities). Immediately after the drought+heat episode, plant water status decreased in both species, as well as the PSII photosynthetic parameters (CYRILLIC CAPITAL LETTER EFPSII and Fv'/Fm'), while non-photochemical quenching increased. However, the gas-exchange parameters of PE and the hybrid responded differently to the combined stress. The hybrid suffered a stronger reduction on the net CO2 assimilation rate and transpiration rate, and presented higher levels of lipid peroxidation, but with no cell membrane permeability injuries. Principal component analysis supports that the different profile of both species is possibly associated to the stronger antioxidant capacity of PE under stress conditions. Moreover, these differences were still observed during recovery and photosynthesis was re-established totally only in PE. The hybrid clearly demonstrated less ability to restore the gas-exchange in the same period, possibly due to stomata re-opening limitations. The low net CO2 assimilation rates in the hybrid after stress relief could also result in the necessity to use the starch reserves to maintain TSS pools available for stress recovery. We conclude that the hybrid perform better under control conditions, and the PE seems better prepared to cope with the predictable global climate change scenarios forecast for the next decades. The hybrid is more affected by drought+heat, but is able to keep a photosynthetic performance close to the PE under stress, although less efficient during recovery.
keywords
OXIDATIVE STRESS; CLIMATE-CHANGE; ABSCISIC-ACID; PLANTS; PHOTOSYNTHESIS; ADAPTATION; TOLERANCE; PROLINE; GROWTH; TAEDA
subject category
Agriculture
authors
Dias, MC; de Oliveira, JMPF; Marum, L; Pereira, V; Almeida, T; Nunes, S; Araujo, M; Moutinho-Pereira, J; Correia, CM; Santos, C
our authors
Tânia Raquel Domingues de Almeida
Post-Doc Fellowshipacknowledgements
This work was financed by the project CENTRO-07-0202-FEDER018579-I&D em tecnologias e t e cnicas de clonagem in vitro, micropropagac ao e clonagem de plantas e genotipos, co-financed by the QREN, Programa Mais Centro -Operacional Regional do Centro and EU through European Regional Development Fund (FEDER), by Fundacao para a Ciencia a Tecnologia (FCT) and Ministerio da Educacao e Ciencia through national fund, and the co-funding by the FEDER, within the PT2020 Partnership Agreement, and COMPETE 2010, within the projects UI0183 -UID/BIA/04004/2020, UIDB/50006/2020 and UIDB/04033/2020 (CITAB). FCT supported the research contract of MC Dias (SFRH/BPD/100865/2014), JMP Ferreira de Oliveira (SFRH/BPD/74868/2010) and L Marum (EECINST/00131/2018), and the doctoral grant of M Araujo (SFRH/BD/116801/2016).