Polyamines (PAs) play diverse roles in plant growth and development, as well as responses to environmental stimuli. In this study, the effects of PAs on rice salt tolerance were investigated. Salt stress resulted in the alteration of endogenous PAs levels in rice roots and leaves, where spermidine (Spd) and spermine (Spm) contents were increased, and putrescine (Put) content was decreased. RT-qPCR analysis revealed that PAs biosynthesis-related genes ADC1, ODC, and Arginase were significantly downregulated by salt treatment; however, SAMDC transcription was significantly upregulated. Exogenous Spm enhanced rice salt tolerance remarkably; however, exogenous Put and Spd undermined rice salt tolerance. Transgenic rice plants overexpressing SAMDC display a higher ratio of Spm/(Put+Spd) and enhanced salt tolerance. Salt stress also increased polyamine oxidase activities in rice, resulting in elevated reactive oxygen species (ROS) production. Our findings revealed that accumulation of Put and Spd substantially reduced salt tolerance in rice, likely by facilitating ROS production; whereas, conversion of Put and Spd to Spm contributes to rice salt tolerance.

多胺（PAs）在植物生长和发育以及对环境刺激的反应中起着多种作用。在这项研究中，研究了PA对水稻耐盐性的影响。盐胁迫导致水稻根部和叶片中内源性PA含量发生变化，亚精胺（Spd）和亚精胺（Spm）含量增加，而腐胺（Put）含量降低。RT-qPCR分析表明，盐处理显着下调了PAs的生物合成相关基因ADC1，ODC和精氨酸酶。但是，SAMDC转录明显上调。外源Spm显着提高了水稻的耐盐性；但是，外源的Put和Spd破坏了水稻的耐盐性。过表达SAMDC的转基因水稻显示更高的Spm /（Put + Spd）比和增强的耐盐性。盐胁迫还增加了水稻中的多胺氧化酶活性，导致活性氧（ROS）产量增加​​。我们的发现表明，Put和Spd的积累可能通过促进ROS的产生大大降低了水稻的耐盐性。而Put和Spd转换为Spm有助于提高水稻的耐盐性。