Developing a Roadmap to Define a Potential Ideotype for Drought Tolerance in Eucalyptus

Climate change is escalating the water crisis worldwide, leading to unpredictable water availability and water scarcity, which is among the main environmental factors affecting plant growth and yield, severely affecting the productivity of planted forests, most of them composed of Eucalyptus species. The selection of genotypes capable of growing and surviving under water scarcity is required for eucalypt cultivation in areas with seasonal or continuous drought episodes. To achieve this goal, there is the current need for the identification of potential drought tolerance bioindicators, which is a challenging task since plant responses to drought involve numerous genes and strategies. We posit that eco-physiological and morphoanatomical analyses in combination with molecular approaches could help fill the current knowledge gap. In this review, we summarize recent advances in the identification of potential indicators of drought tolerance in Eucalyptus and discuss the typical responses to drought stress, as well as their importance as bioindicators for the development of a drought-tolerant eucalypt ideotype. Study Implications: This review sheds light on Eucalyptus characteristics that potentially contribute to drought tolerance in trees of this genus. This knowledge is of paramount importance for the selection and cultivation of the best eucalypt varieties in areas experiencing seasonal or continuous water restriction.