Jupa Radek, Plichta Roman, Paschová Zuzana, Nadezhdina Nadezhda, Gebauer Roman
Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlárská 2, 61137 Brno, Czech Republic.
Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelská 3, 61300 Brno, Czech Republic.
Tree Physiol. 2017 Sep 1;37(9):1182-1197. doi: 10.1093/treephys/tpx072.
Efficient water management is essential for the survival of vascular plants under drought stress. While interrelations among drought stress, plant anatomy and physiological functions have been described in woody dicots, similar research is very limited for non-palm arborescent and shrubby monocots despite their generally high drought tolerance. In this study, potted transplants of Dracaena marginata Lam. in primary growth stage were exposed to several short- and long-term drought periods. Continuous measurements of sap flow and stem diameter, the evaluation of capacitance and leaf conductance, the quantification of non-structural carbohydrates (NSC), and organ-specific anatomical analyses were performed to reveal the mechanisms promoting plant resistance to limited soil moisture. The plants showed sensitive stomata regulation in the face of drying soil, but only intermediate resistance to water loss through cuticular transpiration. The water losses were compensated by water release from stem characterized by densely interconnected, parenchyma-rich ground tissue and considerable hydraulic capacitance. Our results suggest that the high concentration of osmotically active NSC in aboveground organs combined with the production of root pressures supported water uptake and the restoration of depleted reserves after watering. The described anatomical features and physiological mechanisms impart D. marginata with high resistance to irregular watering and long-term water scarcity. These findings should help to improve predictions with respect to the impacts of droughts on this plant group.
高效的水分管理对于维管植物在干旱胁迫下的生存至关重要。虽然在木本双子叶植物中已经描述了干旱胁迫、植物解剖结构和生理功能之间的相互关系，但对于非棕榈树状和灌木状单子叶植物，尽管它们通常具有较高的耐旱性，类似的研究却非常有限。在本研究中，处于初生生长阶段的盆栽龙血树（Dracaena marginata Lam.）被暴露于几个短期和长期干旱时期。通过连续测量液流和茎直径、评估电容和叶片导度、定量非结构性碳水化合物（NSC）以及进行器官特异性解剖分析，以揭示促进植物抵抗土壤水分有限的机制。面对干燥的土壤，这些植物表现出敏感的气孔调节，但对通过角质层蒸腾的水分损失仅具有中等抗性。水分损失通过茎中水分的释放得到补偿，茎的特征是具有紧密相连、富含薄壁组织的基本组织和相当大的水力电容。我们的结果表明，地上器官中高浓度的渗透活性NSC与根压的产生相结合，支持了水分吸收以及浇水后耗尽储备的恢复。所描述的解剖特征和生理机制赋予龙血树对不规则浇水和长期缺水的高抗性。这些发现应有助于改进对干旱对该植物类群影响的预测。
