Abstract
Despite concern about the stress drought imposes on tree species under a warming climate, their molecular responses to drought stress have not been well-documented. We analyzed the transcriptional response of seedling leaves after exposure to short-term drought stress in Fagus crenata. After well-watered and water-stressed treatments, we mapped the RNA-seq reads derived from sampled leaves and identified 127 differentially expressed genes (DEGs), of which 89 were up- and 38 down-regulated in water-stressed plants. Several dozen up-regulated DEGs were predicted to encode proteins that would facilitate mitigating processes or avoid the adverse effects caused by drought stress, including stomatal closure, reactive oxygen species (ROS) scavenging, abscisic acid (ABA) accumulation and response, and osmoprotectants. The evidence of down-regulation in several genes in response to drought stress was in accordance with the results of a literature survey. The functional category of sulfate assimilation was enriched in up-regulated DEGs, although there was also evidence of sulfur deficiency in the DEGs. These results suggest the existence of molecular mechanisms in beech that are common in other plant species, representing an acclimation response to drought stress as well as sulfur metabolism under drought stress conditions. This information provides the basis for further species-specific functional genomic research within the context of a warming climate.