Recently, there is an increased interest in the function of polyamine (PA) catabolism during fruit ripening, but little is known about its role during the ripening of peach (Prunus persica L.). In this study, the contents of both free and conjugated PAs markedly decreased as the peach fruit ripened. However, RNA-seq analysis showed that the transcript levels of PA synthesis–related genes increased, suggesting that the decreasing PA content during peach ripening was associated with PA catabolism. To better understanding the function of PA catabolism in peach ripening, genes encoding potential polyamine oxidases (PAOs), which are involved in PA catabolism, were identified across the peach genome. Four putative PAO genes (PpePAO1-PpePAO4) were identified in peach using the recently released genome database. The mRNA level of PpePAO1 was significantly increased during peach fruit ripening. Detection of free PAs in tobacco leaves transiently over-expressing PpePAO1 suggested that this gene is probably involved in terminal catabolism of PA. Treatment with the PAO inhibitor guazatine significantly reduced ethylene production and flesh softening of peach fruit, decreased the expression levels of fruit ripening-related genes, and significantly decreased the expression level of PpePAO1 and PAO activity, while PA contents were dramatically higher compared to control treatments. Our results suggests that PpePAO1-mediated PA catabolism is associated with decreased PA content during peach fruit ripening. These data provide valuable knowledge for better understanding the roles of PA catabolism in peach development and ripening.

最近，人们对水果成熟过程中多胺（PA）分解代谢的功能越来越感兴趣，但是人们对其在桃子（Prunus persica L.）成熟过程中的作用了解甚少。在这项研究中，随着桃果实的成熟，游离和结合PA的含量均显着降低。但是，RNA-seq分析显示，PA合成相关基因的转录水平增加，表明桃成熟过程中PA含量降低与PA分解代谢有关。为了更好地了解PA分解代谢在桃子成熟中的功能，在整个桃子基因组中鉴定了编码潜在的多胺氧化酶（PAO）的基因，这些基因参与了PA分解代谢。四个推定的PAO基因（PpePAO1-PpePAO4使用最近发布的基因组数据库在桃子中鉴定了）。在桃果实成熟期间，PpePAO1的mRNA水平显着增加。在烟草叶片中短暂过量表达PpePAO1的游离PA的检测表明，该基因可能与PA的最终分解代谢有关。用PAO抑制剂番石榴碱处理可显着降低桃果实的乙烯生成和果肉软化，降低果实成熟相关基因的表达水平，并显着降低PpePAO1和PAO活性的表达水平，而PA含量则显着高于对照处理。 。我们的结果表明，PpePAO1介导的PA分解代谢与桃果实成熟期间PA含量降低有关。这些数据提供了宝贵的知识，有助于更好地了解PA分解代谢在桃子发育和成熟中的作用。