Variation in Brown Rot Susceptibility and Phenolic Profile at Different Stages of Plum Fruit ( <i>Prunus domestica</i> L.) Development

Plum production is severely affected by brown rot caused by <i>Monilinia</i> spp. In this study, the relationship between the content of major phenolic compounds and the severity of brown rot in artificially inoculated fruits of two plum cultivars ("Stanley" and "Čačanska Rodna") was investigated at three fruit developmental stages. The results showed that the phenolic profiles of healthy fruits did not differ significantly between cultivars. In the early stages of brown rot development, some phenolic compounds correlated significantly with lesion diameter in both cultivars. Later, as the disease progressed, negative correlation between disease severity and content of quercitrin, rutin, naringin, isoferulic acid, polydatin, and catechin and positive correlation between disease severity and content of naringenin and aesculetin was found. The most significant correlations were observed in pit hardening and ground color change of fruits, which may reflect potential involvement of these compounds in the susceptibility of plum fruits to <i>Monilinia</i>-induced infections.