Progress on plant orphan genes.

Orphan genes are located in a special evolutionary branch and have no significant sequence similarity with any other identified genes. Orphan genes are prevalent in every species, comparative genomics analyses found that all sequenced species contained a portion of orphan genes, and the number of orphan genes obtained by distinct screening conditions is different. Orphan genes are often associated with various stress responses, species-specific evolution and substance metabolism regulation. However, most of the orphan genes have not been well annotated or even have no recognizable functional domains, which brings some difficulties to the functional characterization of orphan genes. Compared with conserved genes, there is less research on orphan genes, which leads to the possibility that the importance of orphan genes may be "unrewarded". In this review, we summarize the origin and evolution of orphan genes, plant orphan gene screening and functions, and analyse the existing challenges and future research priorities and solutions, which provide theoretical basis for the study of orphan gene function and action mechanisms. 孤基因(orphan genes)处在一个特殊的进化分支上,和其他任何已鉴定的基因没有显著的序列相似性。孤基因普遍存在于每个物种中,比较基因组学分析发现所有已测序的物种中均包含一部分孤基因,不同的筛选条件所获得的数量不等。孤基因经常与各种胁迫响应、物种特异性进化和物质代谢调节相关联。但多数孤基因没有被很好的注释,甚至没有可以被识别的功能结构域,为孤基因的功能表征带来了一定困难。相对于保守基因而言,孤基因的研究较少,这就导致了孤基因的重要性可能被“埋没”。本文从孤基因起源与进化、植物孤基因筛选及功能等方面进行了综述,并分析了目前存在的挑战和未来的研究重点与解决方案,以期为研究孤基因功能及其作用机制提供理论基础。.