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首页> 外文期刊>Environmental and experimental botany >Compatible solutes and metabolites accumulation does not explain partial desiccation tolerance in Hymenoglossum cruentum and Hymenophyllum dentatum (Hymenophyllaceae) two filmy ferns with contrasting vertical distribution
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Compatible solutes and metabolites accumulation does not explain partial desiccation tolerance in Hymenoglossum cruentum and Hymenophyllum dentatum (Hymenophyllaceae) two filmy ferns with contrasting vertical distribution

机译：相容的溶质和代谢物积累不解释Hymenoglossum Cruentum和Hymenophyllum牙本质（Hymenophyllaceae）两种薄膜蕨类植物（Hymenophyllum）的部分干燥耐受性，其具有对比垂直分布

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摘要

Hymenoglossum cruentum (Cay.) Presl. and Hymenophyllum dentatum (Cay.) are poikilohydric partial desiccation tolerant (PDT) epiphytic filmy ferns with contrasting vertical distributions. H. cruentum is restricted to trunk base (ground to 1 m), and H. dentatum is more generalist growing from the ground up to 9 m in the host. Vertical distribution has been related to interspecific differences to cope with greater desiccating conditions such as low humidity and high irradiance. PDT plants exhibit a series of mechanisms that allow them to better tolerate severe dehydration that include the accumulation of compatible solutes, and the de novo synthesis of proteins and free sugars that are thought to protect cellular structure during cycles of desiccation-rehydration. Therefore, inter specific differences in the capacity to accumulate compatible solutes and metabolites during desiccation-rehydration may explain differences in vertical distribution between these two "filmy fern" species. The contents of proline, glycine betaine, soluble sugars, total proteins, and pigments of the photosynthetic system were evaluated during a cycle of desiccation-rehydration in H. cruentum and H. dentatum. The latter exhibited a more rapid desiccation-rehydration cycle in contrast to the former. Soluble sugars, proline, and pigment contents decreased in the dehydrated state. The two filmy ferns did not exhibit a major accumulation of proline (lower than 8 mu mol g(-1) DW) or glycine betaine (lower than 4 mg g(-1) DW) which contrasts with other higher plants exposed to water deficit. Both species exhibited an elevated sugar concentration in the hydrated state, which decreased during desiccation by approximately 2.5-fold. These results differ from previous studies on other desiccation tolerant higher-plants but agree with results from bryophytes. We concluded that accumulation of conventional compatible solutes of higher plants is not part of the dehydration induced mechanisms conferring desiccation tolerance in filmy ferns, and do not explain interspecific differences in vertical distribution of the two species. Therefore, partial desiccation tolerance of filmy ferns probably relies on preformed structural rather than induced biochemical mechanisms, suggesting similarities of Hymenophyllaceae (primitive ferns) with bryophytes.
机译：Hymenoglossum Cruentum（CAY。）PRESL。和Hymenophyllum牙本质（CAY。）是用对比度垂直分布的含水水溶液部分干燥耐受性（PDT）外部薄膜蕨类植物。 H. Cruentum仅限于躯干底座（地面至1米），H. Dentatum在宿主中从地面生长至9米的更广泛。垂直分布与诸如低湿度和高辐照度等更大的干燥条件，术语差异有关。 PDT植物表现出一系列机制，使它们能够更好地耐受严重的脱水，该严重脱水包括兼容溶质的积累，以及蛋白质和游离糖的De Novo合成，被认为在干燥补液循环期间保护细胞结构的蛋白质和游离糖。因此，在干燥补液期间积累相容性溶质和代谢物的能力的特异性差异可以解释这两个“薄膜蕨类植物”物种之间的垂直分布的差异。在H.Cruentum和H.牙本质的干燥补液循环期间评估了脯氨酸，甘氨酸甜菜碱，可溶性糖，总蛋白质和颜料的颜料。与前者相比，后者表现出更快速的干燥补液循环。可溶性糖，脯氨酸和颜料含量在脱水状态下降。两种薄膜蕨类植物没有表现出脯氨酸的主要积累（低于8μmolg（-1）dw）或甘氨酸甜菜碱（低于4mg g（-1）dw），其与暴露于水赤字的其他高等植物形成鲜明对比的。两种物种在水合状态下表现出升高的糖浓度，在干燥期间减少约2.5倍。这些结果与以往的其他干燥耐受性高等植物的研究不同，但同意苔藓植物的结果。我们得出结论，常规相容性溶质的高等植物的积累不是脱水诱导机制的一部分赋予薄膜蕨类植物中干燥耐受的机制，并且不解释两种物种的垂直分布中的差异差异。因此，薄膜蕨类植物的部分干燥耐受性可能依赖于预成型的结构而不是诱导的生化机制，表明Hymenophylaceae（原始蕨类植物）与苔藓植物的相似性。

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