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PNAS:研究者培育出了古代可育的植物

近日,国际著名杂志PNAS在线刊登了国外研究人员的最新研究成果,文章中,研究者从西伯利亚冰下的3万年前的果实组织中重新培育出了一种有繁殖能力的开花植物。

科研人员从埋在西伯利亚冰下的3万年前的果实组织中重新培育出了一种有繁殖能力的开花植物。永冻土——覆盖了地球表面将近20%的一层厚数百米的冰——包含了一大批生物的残骸,其中许多生物已经被科研人员复活了。然而,迄今为止,在这些永冻土沉积层中还没有找到能够成活的开花植物。David Gilichinsky及其同事从埋在西伯利亚东北部Kolyma河岸附近的永冻土沉积层中的一种北极大松鼠的一个化石洞穴中发掘出了更新世草本植物Silene stenophylla的果实和种子。根据这组作者的放射性碳测年分析,他们发现保存在地下38米的零下温度中的这些沉积物是3万年前的。由于这些松鼠的储藏室留住了冰楔和冰冻的沉积物,这组作者提出,这些松鼠的储藏被迅速冰冻而且在没有解冻的情况下保存。

通过组织培养和微繁殖,这组作者用发掘出的果实的胚胎组织再生了有繁殖能力的Silene stenophylla,并把这种植物移栽到了实验室的盆中,一年之后,它们开花、结果并且有了种子;这种再生的植物和现存的S. stenophylla植物是明显不同的表现型。这组作者说,永冻土沉积层可能是一个长久以来被认为灭绝了的野生植物物种和古代基因库的丰富来源。(生物谷Bioon.com)

Regeneration of whole fertile plants from 30,000-y-old fruit tissue buried in Siberian permafrost

Svetlana Yashinaa, Stanislav Gubinb, Stanislav Maksimovichb, Alexandra Yashinaa, Edith Gakhovaa, and David Gilichinskyb,1

Whole, fertile plants of Silene stenophylla Ledeb. (Caryophyllaceae) have been uniquely regenerated from maternal, immature fruit tissue of Late Pleistocene age using in vitro tissue culture and clonal micropropagation. The fruits were excavated in northeastern Siberia from fossil squirrel burrows buried at a depth of 38 m in undisturbed and never thawed Late Pleistocene permafrost sediments with a temperature of −7 °C. Accelerator mass spectrometry (AMS) radiocarbon dating showed fruits to be 31,800 ± 300 y old. The total γ-radiation dose accumulated by the fruits during this time was calculated as 0.07 kGy; this is the maximal reported dose after which tissues remain viable and seeds still germinate. Regenerated plants were brought to flowering and fruiting and they set viable seeds. At present, plants of S. stenophylla are the most ancient, viable, multicellular, living organisms. Morphophysiological studies comparing regenerated and extant plants obtained from modern seeds of the same species in the same region revealed that they were distinct phenotypes of S. stenophylla. The first generation cultivated from seeds obtained from regenerated plants progressed through all developmental stages and had the same morphological features as parent plants. The investigation showed high cryoresistance of plant placental tissue in permafrost. This natural cryopreservation of plant tissue over many thousands of years demonstrates a role for permafrost as a depository for an ancient gene pool, i.e., preexisting life, which hypothetically has long since vanished from the earth‘s surface, a potential source of ancient germplasm, and a laboratory for the study of rates of microevolution.

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