An in planta approach for understanding defense responses in tomato plants against Fusarium oxysporum Schltdl

Fusarium oxysporum Schltdl is considered as one of the most destructive pathogens of tomato. To devise strategies to combat this devastating pathogen, a detailed understanding of its pathogenesis is extremely essential. In this scenario, this study was designed to find out the time course alterations in the contents of different defense parameters during the pathogenesis of F. oxysporum in tomato plants. After inoculation with the pathogen, the level of defense enzymes contents like beta-1,3 glucanase, phenylalanine ammonia-lyase (PAL), peroxidase (PO) and polyphenol oxidase (PPO) were recorded at three different time points (15, 30 and 45 days after pathogen inoculation) of pathogenesis. Furthermore, total phenol and flavonoid contents were quantified, and ferulic acid and p-coumaric acid were measured. Similarly, nitric oxide content was also evaluated. Histological analysis along with proline and total chlorophyll content were examined at three different time-points to check the amount of stress generation. The results showed that at the initial period of infection, accumulation of different defense components like defense enzymes, phenol, flavonoids, phenolic acids and NO were significantly higher, while the pathogen was found to be able to invade the plant by subduing the defense network at the later stages of pathogenesis.