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

## TL;DR

This study explores how tomato plants respond to tobacco mosaic virus infection, focusing on gene activity and changes in plant chemicals over time.

## Contribution

The study reveals novel gene expression patterns and phytochemical changes in tomato plants infected with TMV, offering insights into plant defense mechanisms.

## Key findings

- PR-1 gene activity increased initially after TMV infection, while PR-2 remained elevated throughout.
- HQT and CHS gene transcripts showed alternating up- and down-regulation patterns over time.
- TMV infection altered levels of phenolic, flavonoid, and fatty acid compounds, with some suppressed and others increased.

## Abstract

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 phenylpropanoid pathway genes in tomato plants (Solanum lycopersicum L.) during a period of 2–14 days 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 up-regulation and down-regulation 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 were increased (such as naringenin, rutin, flavone, ferulic acid, and pyrogallol) or significantly 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, focusing on enhancing the levels of such suppressed compounds may be critical for developing plant viral infection management strategies.