Transcriptomic Leaf Profiling Reveals Differential Responses of the Two Most Traded Coffee Species to Elevated [CO2]

Abstract

As atmospheric [CO2] continues to rise to unprecedented levels, understanding its impact on plants is imperative to improve crop performance and sustainability under future climate conditions. In this context, transcriptional changes promoted by elevated CO2 (eCO2) were studied in genotypes from the two major traded coffee species: the allopolyploid Coffea arabica (Icatu) and its diploid parent, C. canephora (CL153). While Icatu expressed more genes than CL153, a higher number of differentially expressed genes were found in CL153 as a response to eCO2. Although many genes were found to be commonly expressed by the two genotypes under eCO2, unique genes and pathways differed between them, with CL153 showing more enriched GO terms and metabolic pathways than Icatu. Divergent functional categories and significantly enriched pathways were found in these genotypes, which altogether supports contrasting responses to eCO2. A considerable number of genes linked to coffee physiological and biochemical responses were found to be affected by eCO2 with the significant upregulation of photosynthetic, antioxidant, and lipidic genes. This supports the absence of photosynthesis down-regulation and, therefore, the maintenance of increased photosynthetic potential promoted by eCO2 in these coffee genotypes.

A Transcriptomic Approach to Understanding the Combined Impacts of Supra-Optimal Temperatures and CO2 Revealed Different Responses in the Polyploid Coffea arabica and Its Diploid Progenitor C. canephora

“…For this, we have used a comparative approach using two coffee genotypes grown under a control temperature of 25/20 • C (day/night) and then gradually exposed to increased temperatures up to 42/30 • C in combination with ambient CO 2 (aCO 2 : 380 µL L −1 ) or elevated CO 2 (eCO 2 : 700 µL L −1 ) air. This analysis is complementary to (and advances) previous studies, in which the plants from these two genotypes showed a temperature tolerance up to 37/28 • C [30], together with an increased photosynthetic potential under eCO 2 [43], which might contribute to the relief of some negative effects imposed by harsh elevated temperatures.…”

“…It increases tree growth and forest productivity [ 65 ], and the photosynthetic tolerance in some C3 plants, including of the coffee genotypes studied here [ 14 , 36 , 41 ]. We have previously shown that under the single factor of eCO 2 , CL153 mostly expressed DEGs associated with general biological processes and to a lower extent to abiotic stress responses, while Icatu increased the upregulation of genes linked to plant tolerance and adaptation to abiotic factors [ 43 ]. The positive effects of eCO 2 in CL153 were also related to an enrichment in the cutin, suberine, and wax KEGG pathway in CL153, which would help to generate more biomass and height than under aCO 2 .…”

“…GO terms associated with RuBisCO were found to be largely up-regulated in Icatu and in CL153 under the single exposure to eCO 2 , supporting the absence of photosynthetic acclimation and the reinforcement of RuBisCO activity [ 13 , 14 ]. In addition, a specific search of the processes that play a major role on the physiological and biochemical acclimation of coffee to several environmental constraints resulted in the identification of 171 DEGs in Icatu and 190 DEGs in CL153 that were significantly affected by eCO 2 [ 43 ], with these numbers being much lower than the ones found here for the combined effects of eCO 2 and high temperatures.…”

“…For instance, it has been observed that in Coffea , eCO 2 promotes a high plant vigor [ 13 ] and even crop yield [ 36 ], while improving tolerance to drought [ 37 , 38 , 39 ] and supra-optimal temperatures [ 14 , 37 , 40 , 41 ], with positive impacts on the physical and chemical traits of the coffee beans under supra-optimal temperatures, contributing to preserve its quality [ 42 ]. We previously showed that eCO 2 causes significant changes in the transcriptomic responses of C. arabica and C. canephora , with differentially expressed genes (DEGs) being much more abundant in the diploid than in C. arabica [ 43 ]. Functional analysis also revealed that under eCO 2 , C. canephora expressed DEGs associated to general biological processes and to a lower extent to abiotic stress responses while C. arabica showed an upregulation of genes linked to plant tolerance, oxidative stress control, aquaporins, reorganization of the lipid matrix membrane, chloroplast/thylakoid organization, and PS II repair.…”

Primary Metabolite Profile Changes in Coffea spp. Promoted by Single and Combined Exposure to Drought and Elevated CO2 Concentration

“…These effects were reported to occur in Coffea spp. as well, where eCO 2 mitigated the negative impacts of drought on photosynthetic performance and components [ 28 , 29 , 30 , 31 , 32 ].…”