Background and aims Plant and bacteria are able to synthesise proline, which acts as a compound to counteract the negative effects of osmotic stresses. Most methodologies rely on the extraction of compounds using destructive methods. This work describes a new proline biosensor that allows the monitoring of proline levels in a non-invasive manner in root exudates and nodules of legume plants. Methods The proline biosensor was constructed by cloning the promoter region of pRL120553, a gene with high levels of induction in the presence of proline, in front of the lux cassette in Rhizobium leguminosarum bv. viciae . Results Free-living assays show that the proline biosensor is sensitive and specific for proline. Proline was detected in both root exudates and nodules of pea plants. The luminescence detected in bacteroids did not show variations during osmotic stress treatments, but significantly increased during recovery. Conclusions This biosensor is a useful tool for the in vivo monitoring of proline levels in root exudates and bacteroids of symbiotic root nodules, and it contributes to our understanding of the metabolic exchange occurring in nodules under abiotic stress conditions.

中文翻译：

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一种用于监测渗透胁迫和恢复下豌豆根分泌物和根瘤中脯氨酸的新型生物传感器

背景和目的 植物和细菌能够合成脯氨酸，脯氨酸作为一种化合物来抵消渗透胁迫的负面影响。大多数方法依赖于使用破坏性方法提取化合物。这项工作描述了一种新的脯氨酸生物传感器，它可以以非侵入性方式监测豆科植物根系分泌物和根瘤中的脯氨酸水平。方法通过克隆pRL120553启动子区构建脯氨酸生物传感器，pRL120553是在脯氨酸存在下具有高水平诱导的基因，位于Rhizobium leguminosarum bv的lux盒前。被害人。结果 游离试验表明脯氨酸生物传感器对脯氨酸敏感且特异。在豌豆植物的根分泌物和根瘤中都检测到脯氨酸。在类杆菌中检测到的发光在渗透胁迫处理期间没有显示出变化，但在恢复期间显着增加。结论 该生物传感器是体内监测共生根瘤根分泌物和类杆菌中脯氨酸水平的有用工具，有助于我们了解非生物胁迫条件下根瘤中发生的代谢交换。