Are tomato plants co-exposed to heat and salinity able to ensure a proper carbon metabolism? – An insight into the photosynthetic hub

Supplementary data to this article can be found online at https://doi.org/10.1016/j.plaphy.2023.108270.

Abiotic stress combinations, such as high temperatures and soil/water salinization, severely threaten crop productivity worldwide. In this work, an integrative insight into the photosynthetic metabolism of tomato plants subjected to salt (100 mM NaCl) and/or heat (42 °C; 4 h/day) was performed. After three weeks, the stress combination led to more severe consequences on growth and photosynthetic pigments than the individual stresses. Regarding the photochemical efficiency, transcript accumulation and protein content of major actors (CP47 and D1) were depleted in all stressed plants, although the overall photochemical yield was not negatively affected under the co-exposure. Gas-exchange studies revealed to be mostly affected by salt (single or combined), which harshly compromised carbon assimilation. Additionally, transcript levels of stress-responsive genes (e.g., HsfA1 and NHX2) were differentially modulated by the single and combined treatments, suggesting the activation of stress-signature responses. Overall, by gathering an insightful overview of the main regulatory hub of photosynthesis, we show that the impacts on the carbon metabolism coming from the combination of heat and salinity, two major conditioners of crop yields, were not harsher than those of single stresses, indicating that the growth impairment might be attributed to a proficient distribution of resources towards defense mechanisms.

The work here presented was partially supported by national funds through the Foundation for Science and Technology (FCT), within UIDB/05748/2020 and UIDP/05748/2020 (GreenUPorto), UIDB/04050/2020 (CBMA), UIDB/50006/2020 (LAQV-REQUIMTE) and UIDB/04033/2020 (CITAB). The authors also recognize the support by the I&D project “AgriFood XXI”, ref. NORTE-01-0145-FEDER-000041, co-financed by the European Regional Development Fund (FEDER), through NORTE 2020 (Northern Regional Operational Program, 2014/ 2020). B. Sousa and D. Moreira also acknowledge FCT for providing PhD student grants (BS: 2020/07826/BD; DM: SFRH/BD/143557/2019).