In the late 19 century, it was discovered that legumes can establish a root nodule endosymbiosis with nitrogen-fixing rhizobia. Soon after, the question was raised whether it is possible to transfer this trait to non-leguminous crops. In the past century, an ever-increasing amount of knowledge provided unique insights into the cellular, molecular, and genetic processes controlling this endosymbiosis. In addition, recent phylogenomic studies uncovered several genes that evolved to function specifically to control nodule formation and bacterial infection. However, despite this massive body of knowledge, the long-standing objective to engineer the nitrogen-fixing nodulation trait on non-leguminous crop plants has not been achieved yet. In this review, the unsolved questions and engineering strategies toward nitrogen-fixing nodulation in non-legume plants are discussed and highlighted.

中文翻译：

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工程固氮结核共生路线图

19世纪末，人们发现豆科植物可以与固氮根瘤菌建立根瘤内共生关系。不久之后，有人提出是否有可能将这一特性转移到非豆科作物上的问题。在过去的一个世纪中，不断增加的知识为控制这种内共生的细胞、分子和遗传过程提供了独特的见解。此外，最近的系统发育学研究发现了一些基因，这些基因进化出专门控制根瘤形成和细菌感染的功能。然而，尽管有如此庞大的知识体系，但在非豆科作物上设计固氮结瘤性状的长期目标尚未实现。在这篇综述中，讨论并强调了非豆科植物固氮结瘤的未解决问题和工程策略。