# Signaling in the Tomato Immunity against _Fusarium oxysporum_
## 2 Results
### Movione Tomato Plants Activate an Early JA-and ABA-Mediated Defense Response after Fol Infection
Asterisks (*) point out statistical differences between mock-inoculated and _Fol_-inoculated MOM and MOV plants according to _t_-test or Mann–Whitney test, with \(p\) < 0.05 (*), \(p\) < 0.01 (**), and \(p\) < 0.001 (***). characterized by an early induction of the JA and ABA pathways, with an antagonistic effect on the SA and ET mediated response at 3 dpi, suggesting that the JA-and ABA-mediated responses could be effective enough to prevent the symptom development and to establish ETI. Levels of Salicylic Acid and Abcisic Acid Are Enhanced in the Susceptible MOM Tomato Plants Infected by Fol  
Levels of the main defense phytohormones SA, ABA, and JA were analyzed in the MOM (susceptible) and MOV (resistant) tomato plants infected with _Fol_ in a time-course study. Figure 3 represents the log(ratio) of the phytohormone accumulation between _Fol_-infected and mock-inoculated plants in both MOM and MOV isogenic lines. A statistically significant accumulation of SA (Figure 3A) and ABA (Figure 3C) was observed in the compatible interaction at 7 dpi. At this time point, the SA and ABA log(ratio) in susceptible tomato plants was around 2.2 and 0.2, respectively, indicating that these phytohormones are involved in the plant response against _Fol_. Besides, SA levels were significantly higher in the susceptible plants at the end of the fungal infection (14 dpi). According to the higher expression of \(LEA\) observed at 3 dpi (Figure 2D), a lower reduction of ABA levels was detected in resistant MOV plants at that time point. In contrast, an inverted pattern was detected for JA (Figure 3B) in this interaction, observing a trend of JA accumulation at 3 dpi in the resistant MOV plants when compared to susceptible MOM. Although no statistical differences were detected in JA levels due to the high variability displayed, these results entirely agree with the \(JAZ7\) induction (Figure 2B), therefore reinforcing the idea that an early activation of the JA pathway occurs in the resistant plants. On the contrary, SA accumulation is a distinctive feature of the susceptibility to _Fol_, perfectly correlating with the _PRI_ expression. Figure 3: Logarithm of the ratios of the SA (**A**), JA (**B**) and ABA (**C**) phytohormone levels in susceptible MOM (MOV; white) and resistant Movione (MOV; gray) tomato plants upon _Fusarium oxysporum_ f. sp. _Ivopersici_ inoculation at 3, 7 and 14 dpi, with respect to the corresponding mock-inoculated plants. Values were expressed as the average log(ratio) of data corresponding to a representative experiment. Asterisks (***) point out statistical differences according to _t_-test or a Mann–Whitney test, with \(p<0.05\) (***), \(p<0.01\) (***) and \(p<0.001\) (***). Susceptible MOM and Resistant MOV Tomato Plants Display Different Volatile Chemical Composition upon Fol Infection  
To identify the VOCs involved in the establishment of ETI, changes in the levels of these metabolites in mock-inoculated and _Fol_-infected MOV and MOM tomato leaves were analyzed by GC-MS at 7 and 14 dpi. Based on the massive dataset obtained (11,505 detected peaks) from the chromatographic study, a principal component analysis (PCA) was performed. The first analysis revealed that both mock-inoculated isogenic lines constitutively emitted a different profile of VOCs (Figure S2). These results could be due to the differences among both isogenic lines caused by the integration of the \(I\) resistance gene in MOV plants. Consequently, the data set was normalized by the mean of the height ions from each mock-inoculated isogenic line to eliminate this metabolic difference, and a new analysis containing the normalized infected plants was performed (Figure 4). The score plot of PCA clearly showed that the first component (PC1) explained changes in the chemical composition of the susceptible and resistant infected tomato plants (21% of variance), while the metabolic alteration during the time course of the experiment was clearly distinguished by the second component (PC2, 13% of variance).