## 3 Discussion
In addition, although salicylic acid (SA) and jasmonic acid (JA) have been known to play important roles in the induced and systemic plant's defense response to pathogenic attack and disease outbreak [39; 40], sometimes, plants may deploy JA and ethylene in salicylic acid-independent endogenous signaling pathways in a manner that circumvents the production of, and signaling by, SA [41; 42]. In fact, the seemingly antagonistic levels of SA and JA in the resistant LA3952 (Figure 4F,H) possibly might have a result of such crosstalk between the salicylic acid-dependent, and the salicylic acid-independent pathways. Particularly puzzling was the dramatic detection of indole-3-acetic acid, IAA in the resistant LA3952 (Figure 4A), yet there was no observable breach in the subject test plants warrants further inquiry to determine if there might be a link with susceptibility and promotion of the pathogen growth associated with the overproduction of this hormone by some plants [43]. In tomato, knocking down IAA results in leaf and fruit deformation phenotypes [44]. However, we did not detect any odd phenotypes on LA3952 as expected on IAA deficient plants. Therefore, it is possible that the absence of detection may be due to technical limitations in the detection and quantification. Volatile Metabolite Profiles Are Differentially Elicited on Susceptible and Resistant Plants in Response to TPP Vectoring or Not the Lso  
Metabolomic approaches have been considered as efficient techniques to examine the profiles of metabolic changes in response to herbivore or pathogen infection, and to identify responsible metabolites associated with resistance or susceptibility [19; 45; 46; 47]. Herbivore-induced plant volatiles have reportedly been involved in indirect defenses in responses to insect herbivory by acting as biochemical cues that attract natural predators [12]. These volatiles are mainly derived from terpenoids, fatty acid, and phenylalanine derivatives [11]. We identified 43 compounds in five main classes--fatty acid-derived, monoterpenes, norisoprenoids, phenylpropanol-derived, and sesquiterpenes (Table 1 and Figure 5). Of the 43, ten chemical species showed some significant low or high levels in an either treatment- or genotype-specific manner. The FA-derived species, hexanal, and (E)-2-hexenal showed abundances of \(\sim\)400% and 40%, respectively, higher in the resistant LA3952 plants treated with TPP-Lso(+) compared to the control and Lso(\(-\)) treatment. A norisoprenoid, \(\beta\)-Ionone was the only other compound to show a similar trend, albeit at a much-reduced abundance (Table 1). \(\beta\)-ionone promotes resistance of tobacco plants against pathogens by functioning as either a signaling molecule or an inducer of signal release involved in the plant defense mechanism [48; 49]. Similarly, FA-derived green leaf volatiles (GLVs), such as hexanal and (E)-2-hexenal are reported to play protective roles in plant fitness by inhibiting the germination of plant pathogens [50; 51; 52]. Furthermore, pathogen-induced (E)-2-hexenal has been reported to possess antimycobacterial activity [53]. Strangely though, three monoterpenes--2-Carene, 3-Carene, and \(\beta\)-Phellandrene were each \(\sim\)50% more abundant in the susceptible CM inoculated with Lso-free TPP, compared to either the control or the Lso(+) plants, even though these three compounds have variously been reported to participate in the defense against insect attack [54; 55]. Still, such observations of the reversal of behavior may not be entirely new since many vector-borne bacterial pathogens are transmitted to the plant host by insect vectors, and this insect-bacteria-plant interaction may modulate both insect fitness and plant-host defensive signaling. The different metabolic profiles between susceptible and resistant plants and the defensive function may be attributed to the composition of terpenoids against phloem-feeding insects [56; 24; 57; 58].