Rate of drying influences tolerance of low water contents in the moss Funaria hygrometrica (Funariaceae)
Rate of drying influences tolerance of low water contents in the moss Funaria hygrometrica (Funariaceae)
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DOI：
10.1639/0007-2745-122.2.271
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
D. McLetchie;L. Stark
中科院分区：
文献类型：
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作者：
D. McLetchie;L. Stark
异水生物体的干燥耐受性 (DT) 取决于四个主要的连续因素：(1) 干燥速率 (RoD)、(2) 由平衡相对湿度 (RHeq) 得出的生物体含水量 (WC)、(3) 干燥事件的持续时间和 (4) 再水合速率 (RoR)。前两个因素经常在实验中结合起来作为干燥的“强度”，因此一个因素对另一个因素的影响相对未知，但在生态上可能很重要。我们假设，更持久的干燥速率应该可以减轻已知诱导性 DT 物种在较低平衡相对湿度下的损害。将培养的苔藓 Funaria hygrometrica 的单克隆芽在五种不同的 RH（12、33、54、75 和 93%）下以不同的 RoD（从完全膨压到卷叶的时间，从 0.067 到 120 小时）干燥，允许在每个 RH 平衡，再水化并在再水化后 0.5 和 24 小时使用叶绿素荧光进行评估。在再水化后 24 小时，F. hygrometrica 的芽经历了快速干燥事件（54%，恢复完全）。在再水化后 0.5 小时，Fv/Fm 水平表明除 93% 之外的所有 RHeq 均受到中度损害，当干燥速率延长时，损害没有减轻。干燥强度通常被解释为耐受干燥速率 × 平衡 RH 组合的能力。通过改变速率在一系列 RHeq 的干燥过程中，发现 F. hygrometrica 能够耐受所有测试的含水量，前提是干燥速率从完全膨压到卷叶至少延长 15 小时。通过采用“逐步下降”干燥方法或此处使用的“湿基质”技术，未来对异水生物体的干燥耐受性的研究可以更准确地评估对干燥胁迫的反应。
Desiccation tolerance (DT) in poikilohydric organisms is dependent upon four principal sequential factors, (1) the rate of drying (RoD), (2) the water content (WC) of the organism deriving from the equilibrating relative humidity (RHeq), (3) the duration of the desiccation event, and (4) the rate of rehydration (RoR). The first two factors are often combined in experiments as the “intensity” of desiccation, and thus the effect of one on the other is relatively unknown but likely to be important ecologically. We hypothesized that more protracted rates of drying should mitigate damage at lower equilibrating RHs in a known inducibly DT species. Cultured uniclonal shoots of the moss Funaria hygrometrica were dried at different RoDs (time from full turgor to leaf curling, from 0.067 to 120 h) at five different RHs (12, 33, 54, 75 and 93%), allowed to equilibrate at each RH, rehydrated and assessed using chlorophyll fluorescence at 0.5 and 24 h postrehydration. At 24 h postrehydration, shoots of F. hygrometrica subjected to a rapid-dry event ( 54%, recovery was complete. At 0.5 h postrehydration, Fv/Fm levels indicated moderate damage at all RHeqs except 93%, with no mitigation of damage when the rate of drying was extended. Intensity of desiccation is normally construed as the ability to tolerate a combination of rate of drying × equilibrating RH. By varying the rate of drying across a range of RHeqs, F. hygrometrica is found to be able to tolerate all water contents tested, providing the rate of drying is extended to at least 15 h from full turgor to leaf curling. By adopting either the “step-down” approach to drying or the “wet substrate” technique used here, future studies on the desiccation tolerance of poikilohydric organisms can more accurately assess responses to desiccation stress.