# Distinct Signatures of Host Defense Suppression by Plant-Feeding Mites
## 2 Results
### Transcriptomic Profiles
#### 2.2.2 Detailed Analysis of Selected Defense-Associated Pathways
\begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} & \multicolumn{1}{c}{**Tel**} \\ \hline \(f\) & **Locus Identifier** & **Amontion (TAC3.2)** & **JA** & **Legic (B1 st-d)** & **Legic (B1 st-d)** & **Legic (B1 st-d)** & **Legic  
\begin{table}
\begin{tabular}{l l c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**\(\boldsymbol{r}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} & \multicolumn{1}{c}{**\(\boldsymbol{\boldsymbol{R}\)**}} \\ \hline
1 & \(\  
Despite the significantly increased concentrations of SA upon all mite infestation treatments, especially upon (dual) infestation with _T. urticae_ (Figure 1D), changes in the relative expression level of genes predicted to be involved in SA biosynthesis, metabolism or signaling were relatively minor (Figure 4). The available gene expression data suggests that SA biosynthesis [68; 69] in tomato upon infestation with mites proceeds via the phenylalanine ammonia lyase (PAL) pathway rather than via the isochorismate synthase (ICS) pathway. Tomato's only _ICS_ (Solyc06g071030) is not represented on our microarray platform, but we confirmed with qPCRs that it was not induced after seven days of feeding by any of our mite species (Figure 5H). In fact, _ICS_ was down-regulated in _A. lycopersici_-infested leaves. Contrary to _ICS_, several early phenylpropanol biosynthetic genes were induced by mite feeding (the phenylpropanol pathway is discusses in more detail in the next section). One out of two chorismate mutase (CM)-encoding genes (Solyc02g088460) was significantly up-regulated in Tu+Te, Tu, Tu+Al and Al samples, but less than 1.5-fold. Genes coding for prephenate aminotransferase (PPA-AT; Solyc04g054710) and aprogenate dehydratase (ADT; Solyc06g074530) enzymes were also up-regulated. The _PPA-AT_ expression pattern was similar to that of CM, while _ADT_ was induced to higher levels. Two _PAL_ genes were significantly up-regulated in Tu samples, similar to the findings of [PERSON] et al. [39], albeit only one (Solyc05g056170) by more than 1.5-fold. Expression of this latter _PAL_ was induced to a similar level in Al, to slightly higher levels in Tu+Al, reduced to a level below the FC cutoff in Tu+Te, and was not significantly induced in Te. Despite their induction, the _CM_, _PPA-AT_, _ADT_ and _PAL_ expression patterns did not match the SA accumulation profiles very well, especially not in leaflets (dual) infested with _T. evansi_. This may be explained by the single and relatively late sampling moment. Additionally, it may be explained by active metabolism of SA. Expression patterns of tomato genes coding for putative homologs of _Arabidopsis thaliana_ SA glycosyltransferases (SAGTs) [70; 71], SA hydroxyles [72; 73] and a dihydroxybenzoic acid glycosyltransferase (DHBAGT) [74], in particular those with the highest BLASTP scores, did not correlate well with SA levels. However, the expression pattern of _salcicylic acid methyltransferase (SAMT;_ Solyc09g091550) matched the SA accumulation profile much better (Figure 4). SAMT catalyzes the methylation of SA, generating volatile methyl salicate (MeSA) in tomato plants [75; 76], and may thereby have control over internal SA pools. At the SA signaling level [68; 77], expression of the tomato gene (Solyc07g040690) that encodes the putative homolog of _A.