Living under a 'dormant' canopy:: a molecular acclimation mechanism of the desert plant Retama raetam
Living under a 'dormant' canopy:: a molecular acclimation mechanism of the desert plant Retama raetam
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DOI：
10.1046/j.1365-313x.2001.00975.x
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发表时间：
2001-02-01
期刊：
影响因子：
7.2
通讯作者：
Cohen, M
中科院分区：
文献类型：
--
作者：
Mittler, R;Merquiol, E;Cohen, M
沙漠植物面临各种环境压力条件，包括缺水、极端温度波动、高辐照度和营养匮乏。因此，在沙漠植物的自然栖息地中研究它们可能会揭示使植物抵抗压力条件的新机制和策略。研究了常绿茎同化荒漠植物雷塔姆对干旱沙丘生态系统的适应。雷塔姆包含两个不同的茎群：暴露在阳光直射下的上层冠层和不受阳光直射的下层冠层。在旱季，冠层上部茎部含有非常低水平的一些必需蛋白质，包括rubisco的大小亚基、抗坏血酸过氧化物酶和光系统II反应中心的D1亚基。然而，编码这些蛋白质的RNA是存在的；细胞质转录本与多体相关，而叶绿体转录本与多体无关。在施水之后，以及在该季节的第一次降雨之后，这些“光合抑制”的茎在6-24小时内恢复并积累了必需蛋白质。相比之下，下冠层的茎在整个旱季都含有必需蛋白质。我们认为，为了在旱季中生存，r.r raetam采用了“部分植物休眠”的适应策略。基因表达的转录后抑制和光合作用的抑制表明，“休眠”是在上层冠层的茎上引起的，上层冠层通过遮荫保护下层冠层。
Desert plants are exposed to a combination of environmental stress conditions, including low water availability, extreme temperature fluctuations, high irradiance and nutrient deprivation. Studying desert plants within their natural habitat may therefore reveal novel mechanisms and strategies that enable plants to resist stressful conditions. We studied the acclimation of Retama raetam, an evergreen stem-assimilating desert plant, to growth within an arid dune ecosystem. Retama raetam contained two different populations of stems: those of the upper canopy, exposed to direct sunlight, and those of the lower canopy, protected from direct sunlight. During the dry season, stems of the upper canopy contained a very low level of a number of essential proteins, including the large and small subunits of rubisco, ascorbate peroxidase and the D1 subunit of the reaction centre of photosystem II. However, RNA encoding these proteins was present; cytosolic transcripts were associated with polysomes, while chloroplastic transcripts were not. Upon water application, as well as following the first rainfall of the season, these 'photosynthetically suppressed' stems recovered and accumulated essential proteins within 6-24 h. In contrast, stems of the lower canopy contained the essential proteins throughout the dry season. We suggest that R. raetam uses an acclimation strategy of 'partial plant dormancy' in order to survive the dry season. 'Dormancy', as evident by the post-transcriptional suppression of gene expression, as well as the suppression of photosynthesis, was induced specifically in stems of the upper canopy which protect the lower canopy by shading.