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 α-limonene, fenchyl alcohol, borneol, 4-terpineol, 4-thujanol, aromadendrene, α-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.

树种的适应性状的种内多样性是决定其在胁迫条件下生存能力的关键因素。通常在受控环境条件下进行体外筛选以评估整棵树对干旱条件的反应，以常规方式选择耐性基因型进行育种和保护计划。本研究表明了两种桉树桉的响应克隆会在形态，生理，生化，分子和代谢物水平上适应渐进的短期水分胁迫条件。根系记录了不同的差异反应：整个克隆中的枝条，比叶面积，相对水含量和叶酚含量。与叶相比，施加胁迫后，两种基因型根组织的生化变化均显着。代谢产物分析表明，在水分胁迫条件下，耐性克隆中积累了α-柠檬烯，薄荷醇，冰片，4-萜品醇，4-thjanjanol，aromadendrene，α-eudesmol和乙酸二十二烷基酯。分子谱分析表明叶片中的胚芽（GER3）和一些转录因子如DREB，CBF2和CBF1c上调在耐性克隆的根组织中。这项研究提出了几个耐受性和易感性克隆的参数，例如根碳水化合物含量，气孔密度和根植物激素水平，这些变异具有明显的变异性，可用于苗圃筛选桉树克隆对水分胁迫的耐受性。