Why could the coffee crop endure climate change and global warming to a greater extent than previously estimated?

Abstract

Coffee, one of the most heavily globally traded agricultural commodities, has been categorized as a highly sensitive plant species to progressive climatic change. Here, we summarize recent insights on the coffee plant's physiological performance at elevated atmospheric carbon dioxide concentration [CO 2 ]. We specifically (i) provide new data of crop yields obtained under free-air CO 2 enrichment conditions, (ii) discuss predictions on the future of the coffee crop as based on rising temperature and (iii) emphasize the role of [CO 2 ] as a key player for mitigating harmful effects of supra-optimal temperatures on coffee physiology and bean quality. We conclude that the effects of global warming on the climatic suitability of coffee may be lower than previously assumed. We highlight perspectives and priorities for further Climatic Change (2019) 152:167-178 https://doi.# The Author(s) 2018research to improve our understanding on how the coffee plant will respond to present and progressive climate change.The current rise in atmospheric carbon dioxide concentration ([CO 2 ]) is one of the major drivers of global warming and climatic change. Atmospheric [CO 2 ] has increased approximately by 43% from the pre-industrial levels of 280 μL L −1 air in 1750 to current levels exceeding 400 μL L −1 air, and global mean surface temperature has increased by 0.85°C over the same period. Depending on the greenhouse gas emission scenarios, projections indicate that, at the end of this century, atmospheric [CO 2 ] might rise between 421 and 936 μL L −1 air, in parallel with a rise in global temperature between 0.3-1.7°C (best scenario) and 2.6-4.8°C (worst scenario), relative to 1986 (IPCC 2013 IPCC 2014). These long-term changes, coupled with climate variability, such as longer and unpredictable droughts and sometimes excessive rainfall, are expected to threaten the sustainability of agricultural production on a global scale, with consequences on the amount and quality of harvestable crops for the actual production areas (DaMatta et al. 2010).Plants sense and respond directly to rising atmospheric [CO 2 ] through an increase in net photosynthesis rate (A) and, frequently, a decrease in stomatal conductance (g s ), and this is the basis for the CO 2 fertilization effect on crops with corresponding increase in yields (Long et al. 2006;Ainsworth and Rogers 2007). Meta-analyses of free-air CO 2 enhancement (FACE) experiments have reported mean reductions in g s of 22% and increases in light-saturated (A) of 31% across a range of C 3 species for an increase in [CO 2 ] from approximately 366 to 567 μL L −1 air (Ainsworth and Rogers 2007). Increases in A with enhanced [CO 2 ] in the chloroplast of C3 plants are associated with a stimulation of the carboxylation rate of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the rate-limiting step in photosynthesis at saturating light and current [CO 2 ] levels, and a concomitant reduction (or even suppression) of its oxygenation function, and thus the rate of photorespiration (Ainsw...

Elevated temperatures impose transcriptional constraints on coffee genotypes and elicit intraspecific differences in thermoregulation

“…1 and 379 Table S1). The present findings are in agreement with recent studies that describe 380 photosynthetic stability, as well as thermoregulatory differences, between coffee 381 genotypes in response to increased growth temperatures (Bertrand et al, 2015;Martins 382 et al, 2016, DaMatta et al, 2019. Comparative studies identifying warm tolerant 383 coffee genotypes are scarce and our results show that, based on the established 384 experimental conditions, cv.…”

“…Minimal impact on 40 photosynthetic-related parameters was observed when various coffee genotypes were 41 exposed to temperatures up to 37°C whereas maximum photosynthetic damage 42 occurred at 42°C for all coffee genotypes . Although coffee 43 presents moderate thermotolerance of photosynthetic-related processes, most 44 genotypes produced abnormal reproductive structures at these elevated temperatures 45 (DaMatta et al, 2019). Accordingly, coffee plants subjected to 45°C for 1-to-1.5 hours 46 showed leaf age-related differences in physiological recovery and did not bear flowers 47 or fruits (Marias et al, 2017a).…”

“…Several studies on the impact of climate change on coffee 5 systems have projected marked negative effects on yield, berry quality, suitable 6 planting areas, and incidence of disease and insects. Collectively, these environmental 7 stresses will likely impose both economic and social problems within many coffee 8 producing regions (reviewed by DaMatta et al, 2019). Despite attenuating factors 9 associated with increasing global CO2 levels that could partially mitigate the negative 10 production trends described above and numerous studies 11 demonstrating the impact of temperature on coffee physiology (Drinnan and Menzel, 12 1995;DaMatta and Ramalho, 2006;Läderach et al, 2017), a detailed understanding of 13 the molecular thermoregulatory mechanisms is lacking.…”

“…Both phenomena are 34 predicted to be more frequent in the future and may occur singly or concomitantly (Hao 35 et al, 2013;IPCC, 2014) highlighting the need for independent and overlapping 36 studies. 37 To understand the limits of coffee thermotolerance, recent studies have explored 38 the effect of a gradual increasing temperature or extreme heat stress on select 39 physiological processes (reviewed by DaMatta et al, 2019). Minimal impact on 40 photosynthetic-related parameters was observed when various coffee genotypes were 41 exposed to temperatures up to 37°C whereas maximum photosynthetic damage 42 occurred at 42°C for all coffee genotypes .…”

“…At 61 present, molecular studies examining the effect of elevated temperature on Coffea sp. 62 are limited when compared to molecular-based drought studies in this crop (Moffato et 63 al., 2016;DaMatta et al, 2019). To the best of our knowledge, a large-scale analysis of 64 3 the intraspecific transcriptional variation in response to elevated temperature has not 65 been reported in Coffee arabica L. and could reveal thermotolerance molecular 66 pathways and important strategies towards breeding programs.…”