Influence of Blueberry Mosaic Disease on Polyphenolic Profile and Antioxidant Capacity of Highbush Blueberry 'Duke' Fruits.

Blueberry mosaic virus (BlMaV) is a persistent pathogen that alters host physiology; however, its impact on secondary metabolism in blueberry fruits remains poorly characterized. In this study, the phenolic profile of the cultivar 'Duke' was systematically examined in healthy and BlMaV-infected plants over two successive years. Using UHPLC Q-ToF MS, a total of 46 phenolic compounds were detected, spanning flavonols, phenolic acids, and anthocyanins. Comparative analyses revealed consistent shifts in metabolite abundance between healthy and infected samples. Several flavonol aglycones and phenolic acid derivatives accumulated in infected fruits, whereas multiple anthocyanins and glycosides were reduced. To further explore metabolic relationships, color correlation analysis highlighted distinct co-variation patterns among compound classes. Principal component analysis clearly separated infected and healthy fruits, confirming that viral infection was the dominant source of variation, surpassing the influence of harvest year or environmental factors. Nevertheless, the antioxidant capacity remained unchanged, regardless of the presence of the virus or the variation in environmental conditions. These results provide novel biochemical evidence that BlMaV infection reshapes the phenolic composition of blueberries and lays the groundwork for future studies on the metabolic consequences of viral stress in fruit crops.