A Transcriptomic Approach to Understanding the Combined Impacts of Supra-Optimal Temperatures and CO₂ Revealed Different Responses in the Polyploid <i>Coffea Arabica</i> and Its Diploid Progenitor <i>C. Canephora</i>

• Main Authors: Isabel Marques, Isabel Fernandes, Octávio S. Paulo, Fernando C. Lidon, Fábio M. DaMatta, José C. Ramalho, Ana I. Ribeiro-Barros
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: International Journal of Molecular Sciences
• Subjects: climate changes; coffee; elevated air (CO₂); functional analysis; high temperatures; leaf RNAseq
• Online Access: https://www.mdpi.com/1422-0067/22/6/3125

Understanding the effect of extreme temperatures and elevated air (CO₂) is crucial for mitigating the impacts of the coffee industry. In this work, leaf transcriptomic changes were evaluated in the diploid <i>C. canephora</i> and its polyploid <i>C. arabica</i>, grown at 25 °C and at two supra-optimal temperatures (37 °C, 42 °C), under ambient (aCO₂) or elevated air CO₂ (eCO₂). Both species expressed fewer genes as temperature rose, although a high number of differentially expressed genes (DEGs) were observed, especially at 42 °C. An enrichment analysis revealed that the two species reacted differently to the high temperatures but with an overall up-regulation of the photosynthetic machinery until 37 °C. Although eCO₂ helped to release stress, 42 °C had a severe impact on both species. A total of 667 photosynthetic and biochemical related-DEGs were altered with high temperatures and eCO₂, which may be used as key probe genes in future studies. This was mostly felt in <i>C. arabica</i>, where genes related to ribulose-bisphosphate carboxylase (RuBisCO) activity, chlorophyll a-b binding, and the reaction centres of photosystems I and II were down-regulated, especially under 42°C, regardless of CO₂. Transcriptomic changes showed that both species were strongly affected by the highest temperature, although they can endure higher temperatures (37 °C) than previously assumed.