The re-establishment of desiccation tolerance in germinated radicles of Medicago truncatula Gaertn. seeds
The re-establishment of desiccation tolerance in germinated radicles of Medicago truncatula Gaertn. seeds
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DOI：
10.1079/ssr2003145
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发表时间：
2003-12-01
影响因子：
2.1
通讯作者：
Leprince, O
中科院分区：
文献类型：
--
作者：
Buitink, J;Vu, BL;Leprince, O
长春紫花苜蓿发芽的种子。通过活体染色试验和再水化后没有恢复生长，可以看出，突出的胚根长度为2.7 mm的胚根在低于0.2 g H2O g(-1) dw的情况下不能存活。通过使用聚乙二醇（PEG）渗透处理结合冷处理，重新建立了干燥耐受性。发芽后恢复干燥耐性的能力限制在胚根长度在1 ~ 3mm之间的生长期。将发芽种子用2.7 mm长的胚根在10℃-1.7 MPa条件下处理3 d，然后干燥至0.04 g H2O g(-1) dw， 90%的种子在复水化后成活并发育为正常幼苗。干燥耐受性也可以在切除的胚根中重新建立，这表明子叶在这个过程中不是必需的。在聚乙二醇孵育后，无论子叶是否存在，在发芽的胚根重新建立耐干燥性之前，蔗糖迅速积累。诱导脱氢酶（MtDHN）基因表达与脱水耐性的重建相关。此外，当氟立酮加入PEG溶液时，PEG诱导的MtDHN表达受到抑制。
Germinated seeds of Medicago truncatula Gaertn. with a protruded radicle length of 2.7 mm did not survive drying below 0.2 g H2O g(-1) dw, as indicated by vital stain assays and the absence of growth resumption after rehydration. The re-establishment of desiccation tolerance was achieved using an osmotic treatment with polyethylene glycol (PEG), combined with a cold treatment. The ability to regain desiccation tolerance after germination was restricted to a period of growth characterized by radicle lengths between 1 and 3 mm. After PEG treatment of germinated seeds with 2.7 mm long radicles at -1.7 MPa at 10degreesC for 3 d and subsequent drying to 0.04 g H2O g(-1) dw, 90% survived and developed into normal seedlings after rehydration. Desiccation tolerance could also be re-established in excised radicles, demonstrating that cotyledons were not essential for this process. Upon PEG incubation, sucrose accumulated rapidly prior to the re-establishment of desiccation tolerance in germinated radicles, regardless of the presence of cotyledons. Induction of MtDHN (a dehydrin) gene expression was correlated with the re-establishment of desiccation tolerance. Furthermore, the PEG-induced expression of MtDHN was repressed when fluridone was added to the PEG solution.