Characterization of Eucalyptus camaldulensis clones with contrasting response to short-term water stress response

The intra-specific diversity of adaptive traits in tree species is a key factor determining their survivability under stress conditions. In vitro screening under controlled environmental conditions to evaluate the whole-tree response to drought condition is routinely employed to select tolerant genotypes for breeding and conservation programs. The present study demonstrates the response of two Eucalyptus camaldulensis clones to progressive short-term water stress condition at morphological, physiological, biochemical, molecular and metabolite levels. Distinct differential response was recorded in root: shoot, specific leaf area, relative water content and leaf phenol content across the clones. The biochemical changes were significant in root tissues of both genotypes after stress imposition when compared to leaf. Metabolite profiling revealed accumulation of alpha-limonene, fenchyl alcohol, borneol, 4-terpineol, 4-thujanol, aromadendrene, alpha-eudesmol and eicosyl acetate in tolerant clone under water stress condition. Molecular profiling documented up-regulation of germin (GER3) in leaf and several transcription factors like DREB, CBF2 and CBF1c in root tissues of tolerant clone. This study has presented several parameters with distinct variation across the tolerant and susceptible clone like root carbohydrate content, stomatal density and root phytohormone level, which can be used for nursery screening of Eucalyptus clones for water stress tolerance.

Automated summary

The intra-specific diversity of adaptive traits in tree species plays a crucial role in determining survivability under stress conditions. In vitro screening is commonly used to select tolerant genotypes for breeding programs, and this study demonstrated how two Eucalyptus camaldulensis clones responded to short-term water stress at various levels. Differential responses were observed in morphological, physiological, biochemical, molecular, and metabolite aspects, highlighting the importance of certain parameters like root carbohydrate content and stomatal density in screening for water stress tolerance.