University of California, Santa Cruz, Santa Cruz, CA, USA.
Pepperdine University, Malibu, CA, USA.
J Exp Bot. 2020 Jan 23;71(3):1139-1150. doi: 10.1093/jxb/erz472.
Desiccation-tolerant (DT) organisms can lose nearly all their water without dying. Desiccation tolerance allows organisms to survive in a nearly completely dehydrated, dormant state. At the cellular level, sugars and proteins stabilize cellular components and protect them from oxidative damage. However, there are few studies of the dynamics and drivers of whole-plant recovery in vascular DT plants. In vascular DT plants, whole-plant desiccation recovery (resurrection) depends not only on cellular rehydration, but also on the recovery of organs with unequal access to water. In this study, in situ natural and artificial irrigation experiments revealed the dynamics of desiccation recovery in two DT fern species. Organ-specific irrigation experiments revealed that the entire plant resurrected when water was supplied to roots, but leaf hydration alone (foliar water uptake) was insufficient to rehydrate the stele and roots. In both species, pressure applied to petioles of excised desiccated fronds resurrected distal leaf tissue, while capillarity alone was insufficient to resurrect distal pinnules. Upon rehydration, sucrose levels in the rhizome and stele dropped dramatically as starch levels rose, consistent with the role of accumulated sucrose as a desiccation protectant. These findings provide insight into traits that facilitate desiccation recovery in dryland ferns associated with chaparral vegetation of southern California.
耐旱（DT）生物可以在几乎失去所有水分的情况下存活。耐旱性使生物能够在几乎完全脱水、休眠的状态下生存。在细胞水平上，糖和蛋白质稳定细胞成分并防止它们受到氧化损伤。然而，关于维管 DT 植物的整个植物复苏的动态和驱动因素的研究很少。在维管 DT 植物中，整个植物的干燥恢复（复苏）不仅取决于细胞的再水合，还取决于具有不同水分获取途径的器官的恢复。在这项研究中，原位自然和人工灌溉实验揭示了两种耐旱蕨类植物的干燥恢复的动态。器官特异性灌溉实验表明，当水供应给根部时，整个植物可以复活，但仅叶片水合（叶面吸水）不足以使中柱和根重新水合。在这两个物种中，向切除干燥叶片的叶柄施加压力可以使远端叶片组织复活，而仅毛细作用不足以使远端羽片复活。在重新水合时，根茎和中柱中的蔗糖水平急剧下降，而淀粉水平上升，这与积累的蔗糖作为干燥保护剂的作用一致。这些发现为与南加州的疏林植被相关的旱地蕨类植物的干燥恢复提供了特征方面的见解。
