# Distinct Signatures of Host Defense Suppression by Plant-Feeding Mites
## 2 Results
### Transcriptomic Profiles
#### 2.2.2 Detailed Analysis of Selected Defense-Associated Pathways  
JA Pathway  
In general, jasmonate concentrations in mite-infested leaflets (Figure 1A-C) correlated well with both the detected number of DEGs with a predicted function in JA biosynthesis, metabolism or signaling as well as with the magnitude of their expression (Figure 3). Concurrent with the highly increased accumulation of jasmonates in leaflets (dual) infested with _T. urtiae_, the majority of genes encoding (putative) JA biosynthesis enzymes [55], including phospholipes (PLs), lipoxygenases (LOXs), allene oxide cyclase (AOC), allene oxide synthase (AOC) and OPDA reductase 3 (OPR3), were significantly up-regulated in Tu+Te, Tu and Tu+Al samples (Figure 3). By contrast, the expression of just two JA biosynthesis genes (_PLA1_ and _AOS_) was significantly up-regulated in _T. eansi_-infested leaflets. In the Al samples, _PLs_, _LOXs_ and _AOS_ were up-regulated, but expression of _AOC_ was not significantly altered, while _OPR3_ was induced, but less than 1.5-fold. In addition, a putative jasmonate methyltransferase (JMT)-encoding gene (Solyc02g084950) was significantly induced in Tu+Al and Al samples. Note that the gene coding for JAR1, i.e., the enzyme that catalyzes the conjugation of JA and Ile [56], is not present on our microarray. Immediately downstream from JA-Ile accumulation, i.e., at the JA-Ile perception and signaling level [55; 57], multiple JASMONATE ZIM DOMAIN (JAZ)-encoding genes were induced upon each of the mite infestation treatments. _JAZ_ induction, both in terms of gene numbers and magnitude of expression, was highest upon (dual) infestation with _T. urticae_ and lowest with _T. evansi_ (Figure 3). Expression of _COII_ and _MYC_2 was not significantly altered in mite-infested plants. Figure 3: Gene-expression heat map depicting the relative transcript levels of tomato (_Solanum lycopersicum_) genes that encode proteins with a (predicted) function in the jasmonic acid (JA) pathway and that were differentially expressed in leaves after seven days of infestation with herbivorous mites. Tomato leaves were infested with either a single mite species (_Tetranychus urticae_ (Tu), _Tetranychus evansi_ (Te), or _Aculops lycopersici_ (Al)) or two species simultaneously (_T. urticae_ plus _T. evansi_ (Tu+Te), or _T. urticae_ plus _A. lycopersici_ (Tu+Al). Non-infested plants served as controls and were used as a common reference in the transcriptional comparisons. Presented genes were differentially expressed ([PERSON] and [PERSON] false discovery rate adjusted \(p\leq 0.05\); Log\({}_{2}\) fold change (FC) \(\geq 0.585\)) in at least one of the mite-infestation treatments. The different (sub)sections of the pathway are specified on the left. Dark green squares in the leftmost column denote that transcription of the respective gene was found to be significantly induced in the tomato JA-biosynthesis mutant _def-1_, 24 h after exogenous application of JA (for details see [39]). Further downstream, concentrations of jasmonates still correlated well with the expression patterns of defense-associated genes in the Tu and Te samples, but no longer in the other samples, presumably due to suppression by _T. evansi_ and _A. lycopersici_, respectively. In tomato, JA-induced responses to arthropod herbivores typically involve the production of various types of defensive proteins that have antinutritive properties [58], such as: proteinase/protease inhibitors (PIs) [59; 60; 61], arginases [62], threonine deaminases (TDs) [63; 62], polyphenol oxidases (PPOs) [64], and possibly leucine aminopeptides (Laps) [65; 66]. These defensive proteins exert their antinutritive activity inside the herbivore's digestive tract, thus after ingestion of plant material [58; 67]. Multiple tomato genes encoding defensive antinutritive proteins of every class described above, except for TDs, were strongly up-regulated in the Tu samples (Figure 3).