Drought tolerance acquisition in Eucalyptus globulus (Labill.): a research on plant morphology, physiology and proteomics.

Plants perceiving drought stress activate multiple responses to synchronise developmental and molecular activities aimed at improving survival. In this study we attained a multidisciplinary approach to examine the interplay among plant morphology, physiology and proteomics for understanding the mechanisms underlying the adaptive response to drought stress. The stress-related phenotype, the differential expression of putative members of the LEA family of proteins, the seed proteomic profile, and the endogenous content of free and conjugated abscisic acid (ABA and ABAGE) were analysed in two Eucalyptus globulus provenances with contrasting drought tolerance. Differences in morphology were noticeable, drought-tolerant genotypes displaying smaller seeds with higher desiccation in the mature state and a more developed root system that was not reduced under water stress treatments. From physiological and molecular points of view, the endogenous contents of ABA and ABAGE were also higher in the tolerant provenance, as well as the accumulation of proteins involved in abiotic stress tolerance processes. In addition, evidence of two immunologically-related proteins to the maize RAB17 and RAB28 proteins is first reported in Eucalyptus, showing similarities between species. Our results show that E. globulus displays simultaneous adjustments for acquiring drought tolerance that are expressed at physiological, developmental and molecular levels.