University of California, 130 McAllister Way, Santa Cruz, CA, 95060, USA.
California State University, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA.
New Phytol. 2019 Oct;224(1):97-105. doi: 10.1111/nph.16067. Epub 2019 Aug 2.
Desiccation-tolerant (DT) plants can dry past -100 MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro-computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.
耐旱（DT）植物可以在 -100 MPa 以下干燥，并在重新水合后恢复功能。维管 DT 植物面临着在不造成结构损伤的情况下干燥和再水合复杂组织的独特挑战。然而，这些动态在完整的 DT 植物中尚未得到研究。我们使用高分辨率微计算机断层扫描（microCT）、光学显微镜和荧光显微镜来描述完整 DT 蕨类植物叶柄（茎干）组织干燥和再水合的动态。在干燥过程中，木质部导管在茎干细胞脱水之前就发生了栓塞。在复活过程中，木质部重新充满之前，茎干维管束中的叶肉和韧皮部就已经重新水合。我们确定了一些可能有助于维管束干燥和复活的独特茎干特征，包括木质部导管含有果胶（可能赋予其柔韧性和润湿性）；木质部管胞中的叶绿体；以及富含疏水性物质的内皮层，这些物质可以阻止质外体渗漏，同时促进水在维管束内向上流动。复活蕨类植物是研究完整植物叶柄中极端脱水恢复和栓塞修复的新系统。这里鉴定的独特解剖特征可能有助于解释在干燥和复活过程中观察到的水分运动的时空动态。
