Resurrection plants of the genus Ramonda: prospective survival strategies – unlock further capacity of adaptation, or embark on the path of evolution?
Resurrection plants of the genus Ramonda: prospective survival strategies – unlock further capacity of adaptation, or embark on the path of evolution?
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DOI：
10.3389/fpls.2013.00550
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发表时间：
2014-01
影响因子：
5.6
通讯作者：
T. Rakić;Maja Lazarević;Ž. Jovanović;S. Radović;S. Siljak-Yakovlev;B. Stevanović;V. Stevanović
中科院分区：
文献类型：
--
作者：
T. Rakić;Maja Lazarević;Ž. Jovanović;S. Radović;S. Siljak-Yakovlev;B. Stevanović;V. Stevanović
Ramonda 单系古特有种（R. myconi、R. serbica 和 R.~nathaliae）是欧洲第三纪热带和亚热带植物区系的残余。它们是北半球温带地区罕见的复活植物。 Ramonda serbica 和 R. nathaliae 在巴尔干半岛有地域差异，并且在峡谷和山坡的石灰质北坡上拥有相似的栖息地。它们在春季、深秋甚至冬季都保持充足的水分。夏季和初秋，当植物遭受干旱和热胁迫时，其耐旱能力开始发挥作用，进入复苏状态。调查显示，泛素及其结合物、大量草酸和脯氨酸永久存在。两个物种都是同型叶绿素的。它使它们能够在补水后快速恢复光合作用，但也使它们容易受到活性氧形成的影响。脱水会引起抗氧化酶（抗坏血酸过氧化物酶、谷胱甘肽还原酶、多酚氧化酶）的激活，增加 AsA 和 GSH、酚酸、脱水素、蔗糖和无机离子的含量。质膜的特点是胆固醇含量高，膜流动性降低主要是由于脂质饱和水平的增加。细胞遗传学分析表明，R. nathaliae 是二倍体 (2n = 48)，可能是进化较古老的物种，而 R. serbica 是六倍体 (2n = 144)。两个物种仅生活在两个地方，形成杂交个体 (2n = 96)。多倍化是Ramonda属的主要进化机制，与杂交能力一起表明这些保留了古老生存策略的孑遗物种并不是进化的“死胡同”。Ramonda属的物种是有希望的数据来源，对于理解复活植物的复杂生存策略非常重要，通过其进化和对多种环境胁迫的适应潜力进行评估。
Paleoendemic species of the monophyletic genus Ramonda (R. myconi, R. serbica and R.~nathaliae) are the remnants of the Tertiary tropical and subtropical flora in Europe. They are the rare resurrection plants of Northern Hemisphere temperate zone. Ramonda serbica and R. nathaliae are chorologically differentiated in the Balkan Peninsula and occupy similar habitats in calcareous, northward slopes in canyons and mountainsides. They remain well-hydrated during spring, late autumn and even in winter. In summer and early autumn when plants are subjected to drought and thermal stress, their desiccation tolerance comes into operation and they fall into anabiosis. Investigations revealed the permanent presence of ubiquitine and its conjugates, high amounts of oxalic acid and proline. Both species are homoiochlorophyllous. It enables them to rapidly resume photosynthesis upon rehydration, but also makes them susceptible to reactive oxygen species formation. Dehydration induces activation of antioxidative enzymes (ascorbate peroxidase, glutathione reductase, polyphenol oxidase), increase in amounts of AsA and GSH, phenolic acids, dehydrins, sucrose, and inorganic ions. Plasma membranes, characterized by high amount of cholesterol, are subjected to decrease in membrane fluidity mostly on account of increased level of lipid saturation. Cytogenetic analysis revealed that R. nathaliae is a diploid (2n = 48) and probably evolutionary older species, while R. serbica is a hexaploid (2n = 144). Two species live together in only two localities forming hybrid individuals (2n = 96). Polyploidization is the major evolutionary mechanism in the genus Ramonda that together with hybridization ability indicates that these relict species which have preserved an ancient survival strategy are not the evolutionary “dead end.”The species of the genus Ramonda are promising sources of data important for understanding the complex strategy of resurrection plants’ survival, appraised through a prism of their evolutionary and adaptive potential for multiple environmental stresses.