Transcriptional responses and secondary metabolites variation of tomato plant in response to tobacco mosaic virus infestation

The present study focused on the impact of infection with the tobacco mosaic virus (TMV) Specifically, changes in phytochemicals and gene activity related to pathogenesis-related and the phenylpropanoid pathway genes in tomato plants ( Solanum lycopersicum L.) during a period of 2-to-14-day post inoculation (dpi). According to TEM investigation and coat protein sequence analysis, the purified TMV Egyptian AM isolate (PP133743) has a rod-shaped structure with a diameter of around 110 nm. The RT-qPCR analysis revealed that PR-1 showed an initial increase after TMV infection, as seen in the time-course analysis. In contrast, PR-2 was consistently elevated throughout the infection, suggesting a stronger reaction to the virus and suppressing PAL expression at 6 to 14 dpi. The expression levels of HQT and CHS transcripts exhibited alternating patterns of upregulation and downregulation at different time intervals. The HPLC and GC-MS analysis of control and TMV-infected tomato extracts revealed that different phenolic, flavonoid, and fatty acid compounds could be increased (such as naringenin, rutin, flavone, ferulic acid, and pyrogallol) or decreased (such as salicylic acid and chlorogenic acid) after TMV infection. The ability of TMV to inhibit most polyphenolic compounds could potentially accelerate the viral life cycle. Consequently, working to increase such suppressed compounds in tomato plants could be important for developing the management of plant viral infections.