Anthocyanins, an important class of pigmented and health-promoting plant secondary metabolites, are involved in protecting plants from stresses. However, the contribution of anthocyanins in plant resistance to biotic stresses is poorly understood compared with that in plant resistance to abiotic stresses. Here, we characterized the function of anthocyanins in protecting fruit from green mold, the major postharvest disease of citrus fruit. Compared with other oranges, ‘Tarocco’ orange, one of the most important blood oranges enriched in anthocyanins, showed reduced susceptibility to the necrotrophic fungus Penicillium digitatum (Pd) which causes citrus postharvest green mold. Pd infection induced the accumulation of anthocyanins in ‘Tarocco’ orange and exogenous treatment of anthocyanins significantly reduced the susceptibility of citrus fruit to Pd. The accumulation of reactive oxygen species (ROS), which was shown to contribute to plant infection of necrotrophic fungal pathogens, in ‘Tarocco’ orange was less than that in other oranges upon Pd infection. ROS content and associated gene expression in citrus fruit upon Pd infection were reduced after exogenous treatment of anthocyanins. Moreover, transcriptome analysis showed that a lot of genes probably participated in plant–pathogen interaction and anthocyanin biosynthesis were noticeably up-regulated in ‘Tarocco’ orange upon Pd infection. These findings highlight the contribution of anthocyanins to fruit disease resistance and provide significant insights into the control of citrus postharvest green mold.

花青素是一类重要的有色素和促进健康的植物次生代谢物，参与保护植物免受胁迫。然而，与植物对非生物胁迫的抗性相比，花青素在植物对生物胁迫抗性中的作用知之甚少。在这里，我们表征了花青素在保护水果免受绿色霉菌（柑橘类水果的主要采后病害）中的作用。与其他橙子相比，'Tarocco' 橙子是最重要的富含花青素的血橙之一，对导致柑橘采后绿色霉菌的坏死性真菌指状青霉( Pd ) 的易感性降低。钯感染诱导了'Tarocco'橙中花青素的积累，花青素的外源处理显着降低了柑橘类水果对Pd的敏感性。在Pd感染后，'Tarocco' 橙中活性氧 (ROS) 的积累被证明有助于植物感染坏死性真菌病原体。外源性花青素处理后，柑橘类水果在Pd感染后的ROS 含量和相关基因表达降低。此外，转录组分析表明，许多基因可能参与植物 - 病原体相互作用和花青素生物合成在Pd 后在'Tarocco' 橙中显着上调。感染。这些发现突出了花青素对水果抗病性的贡献，并为柑橘采后绿色霉菌的控制提供了重要的见解。