Fusarium core rot disease affects physicochemical and pathophysiological attributes of apple (Malus x domestica Borkh.) fruit

Core rot is becoming an important post-harvest disease in parts of North-Western Himalayan Region due to changing climate. In the present study, the causal organism of core rot was determined, and the potential effects of core rot disease on apple nutrition, vitamins and antioxidants potential were also studied. Based on morphological, molecular (TEF 1 and ITS gene) and Koch postulates studies of collected isolates, the causal fungus was identified as Fusarium fujikuroi. To the best of our knowledge, this is the first report of core rot of apple caused by Fusarium fujikuroi in India. Core rot reduced the nutritional value of apple cultivars, viz., 'Golden Delicious' and 'Royal Delicious', after 10 and 20 d of infection. The disease showed to have decay and rotting of the fruit, resulting in a loss of essential nutrients. This led to decreased levels of DPPH, carotenoid, phenols, acidity, total soluble solid, sucrose, amino acid, ascorbic acid, and anthocyanin in the affected portions of the inoculated fruit. The core rot disease was reported to influence the extent of these effects on sucrose, and TSS properties also. Total soluble sugar content was increased 1.91 and 1.21-fold in 'Golden Delicious' and 'Royal Delicious' fruit respectively after 20 d of inoculation. Additionally, the presence of F. fujikuroi triggered enzymatic reactions that further degrade antioxidants, reducing their levels in the infected areas. Our study showed that changes in the type and concentration of polyphenolic compounds were observed in infected apples compared to healthy apples. The outcome from this study will be beneficial to understand the host-pathogen interaction and for strategic management of this disease under field conditions.