Temperature Impacts the Response of Coffea canephora to Decreasing Soil Water Availability

Climate change is expected to result in more frequent periods of both low rainfall and above normal temperatures for many coffee growing regions. To understand how coffee reacts to such change, we studied the physiological and gene expression responses of the clonal variety C. canephora FRT07 exposed to water deficits under two different temperature regimes. Variations in the time-dependent impact of water deficits on leaf stomatal conductance and carbon assimilation were significantly different under the 27 °C and 27 °C/42 °C conditions examined. The physiological responses 24 h after re-watering were also different for both conditions. Expression analysis of genes known to respond to water deficits indicated that drought-related signaling occurred at both temperatures. Deeper insights into the response of coffee to water deficits was obtained by RNASeq based whole transcriptome profiling of leaves from early, late, and recovery stages of the 27 °C experiment. This yielded expression data for 13,642 genes and related differential expression analysis uncovered 362 and 474 genes with increased and decreased expression, respectively, under mild water deficits, and 1627 genes and 2197 genes, respectively, under more severe water deficits. The data presented, from a single clonal coffee variety, serves as an important reference point for future comparative physiological/transcriptomic studies with clonal coffee varieties with different sensitivities to water deficits and high temperatures. Such comparative analyses will help predict how different coffee varieties respond to changing climatic conditions, and may facilitate the identification of alleles associated with high and low tolerance to water deficits, enabling faster breeding of more climate-smart coffee trees.