Savi Tadeja, Marin Maria, Luglio Jessica, Petruzzellis Francesco, Mayr Sefan, Nardini Andrea
Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italia.
Department of Botany, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria.
Funct Plant Biol. 2016 Apr;43(4):370-379. doi: 10.1071/FP15324.
Functional coordination between leaf and stem hydraulics has been proposed as a key trait of drought-resistant plants. A balanced water transport efficiency and safety of different plant organs might be of particular importance for plant survival in the Mediterranean climate. We monitored seasonal changes of leaf and stem water relations of Salvia officinalis L. in order to highlight strategies adopted by this species to survive in harsh environmental conditions. During summer drought, the water potential dropped below the turgor loss point thus reducing water loss by transpiration, whereas the photosynthetic efficiency remained relatively high. Leaves lost their water transport efficiency earlier than stems, although in both plant organs P50 (water potential inducing 50% loss of hydraulic conductivity) indicated surprisingly high vulnerability when compared with other drought-tolerant species. The fast recovery of leaf turgor upon restoration of soil water availability suggests that the reduction of leaf hydraulic conductance is not only a consequence of vein embolism, but cell shrinkage and consequent increase of resistance in the extra-xylem pathway may play an important role. We conclude that the drought tolerance of S. officinalis arises at least partly as a consequence of vulnerability segmentation.
叶片与茎干水力之间的功能协调被认为是抗旱植物的一个关键特征。对于在地中海气候下生存的植物而言，不同植物器官间平衡的水分运输效率和安全性可能尤为重要。我们监测了药用鼠尾草叶片与茎干水分关系的季节性变化，以突出该物种在恶劣环境条件下生存所采用的策略。在夏季干旱期间，水势降至膨压丧失点以下，从而减少了蒸腾作用导致的水分流失，而光合效率仍相对较高。叶片比茎干更早丧失水分运输效率，尽管与其他耐旱物种相比，这两个植物器官的P50（导致水力导度丧失50%的水势）显示出惊人的高脆弱性。土壤水分供应恢复后叶片膨压的快速恢复表明，叶片水力导度的降低不仅是叶脉栓塞的结果，细胞收缩以及由此导致的木质部外途径阻力增加可能也起着重要作用。我们得出结论，药用鼠尾草的耐旱性至少部分源于脆弱性分割。
