Plants have developed several strategies to overcome the broad scope of environmental challenges imposed by biotic and abiotic stresses, including chemical defenses known as secondary metabolites, natural products or, more recently, specialized metabolites, i.e. chemicals often not present in all plant species, which are mostly involved in ecochemical interactions. Nonprotein amino acids (NPAAs) comprise a large heterogeneous group of nitrogen-containing specialized metabolites with wide distribution in the Plant Kingdom, commonly found in several genera of Fabaceae. Various examples of toxic effects attributed to the NPAAs on animal, microbial and other plant cells are known and often related to their structural similarities to protein amino acids (PAAs). However, NPAAs have also been shown to play important roles in planta as protectant molecules against oxidative damage, besides increasing tolerance of different plant species to a variety of abiotic-induced stresses, such as drought, salinity, and temperature. In this review, we discuss well-established and novel functions recently unveiled for NPAAs, besides alternative modes of action proposed for these metabolites as key mediators and effectors in responses to abiotic stresses.

植物已经开发出几种策略来克服生物和非生物胁迫带来的广泛环境挑战，包括被称为次生代谢产物，天然产物或最近的专门代谢产物的化学防御，即通常在所有植物物种中都不存在的化学物质。主要参与生态化学相互作用。非蛋白质氨基酸（NPAA）包含大量异质的含氮专门代谢物，在植物界广泛分布，通常在Fabaceae的几个属中发现。已知NPAA对动物，微生物和其他植物细胞的毒性作用的各种实例是已知的，并且通常与它们与蛋白质氨基酸（PAA）的结构相似性有关。但是，NPAA也已显示出重要作用除了增加不同植物对各种非生物诱导的胁迫（如干旱，盐分和温度）的耐受性外，植物中的抗氧化保护分子。在本综述中，我们讨论了最近针对NPAA公开的功能完善且新颖的功能，此外还提出了针对这些代谢产物的替代作用方式，这些代谢物作为对非生物胁迫的关键介质和效应物。