Transcriptomic response in foliar and root tissues of a drought-tolerant Eucalyptus globulus genotype under drought stress

Key message Identification of the potential candidate genes involved in drought tolerance in leaves and roots ofEucalyptus globulus. Eucalyptus globulus is one of the most cultivated forest tree species in the world because of its excellent wood properties; however, climate change is affecting its establishment, survival and productivity due to the presence of new events with abiotic and biotic stresses. Among abiotic stresses, drought is becoming a major issue due to long periods of drought in several countries where this species is used in commercial plantations. In this study, RNA-Seq analysis was performed in a tolerant genotype of E. globulus to identify the main genes induced by drought stress (DS) in leaves and roots. A total of 686 sequences in leaves and 438 in roots corresponded to differentially expressed genes (DEGs) when comparing DS plants with control plants. Genes involved in protection against reactive oxygen species (ROS), chaperones, transcription factors and secondary metabolism were upregulated by DS in both tissues. Downregulated genes were involved in photosynthesis, generation of precursor metabolites and energy (leaves), and low oxygen and hormone metabolism (roots). A second experiment was carried out to compare some selected candidate genes between genotypes contrasting in drought tolerance. According to qRT-PCR analysis, genes coding for a bifunctional lipid-transporting protein (EuglLTP2) and geraniol 8 hydroxylase (EuglGER) were induced by drought stress in roots of the tolerant genotype but not in the susceptible genotype. The data generated in this study may form the basis for future research to identify drought tolerance mechanisms in E. globulus. They are also useful for use in genetic improvement programs.