## 3 Discussion  
The results of this study document the volatiles emitted from photoplasma infected cabbage palms in Florida, nearby palms that are threatened but uninfected (based on symptoms), and healthy palms far removed from areas with significant disease spread. These data provide the first known classification of GLVs emitted from palms infected with photoplasmas. Chromatographic profiles involved in the suppression or increase in the Intensity of some major compounds were identified. The overexpression of the results of these analyses showed that the chromatographic profiles of \(I\), _NIT_, and _NINT_ palms were different in terms of the composition of the GLVs mixture. Two of the five volatiles assessed, i.e., hexanal and E-2-hexenal, were present in significantly higher concentrations in \(I\) palms than in _NIT_ and _NINT_ palms. While these compounds appear be emitted in higher concentrations from LB infected palms, they are emitted by all plants sampled, likely due to the fact that despite other palms not being infected with LB, the study was conducted in a natural/non-sterile setting; therefore, the presence of these volatiles from other palms is likely due to the fact that other types of biotic stresses are present in all plants (general herbivory, non-lethal pathogens) and also cause emission of these volatiles. The significant drop in emission of these volatiles in  
Figure 6: Box chart displaying volatile concentration across replicates in cabbage palms classified as infected (_I_); (**A**) hexanal, (**B**) E-2-hexenal, (**C**) Z-3-hexen-1-o 1 and (**D**) 1-hexanol; blue = replicate 1, orange = replicate 2; \(y\)-axis is GC/Mass Spec unit concentration. Spa_1 between replicates is due to the fact that the first experiment was conducted when the palm was still alive, with moderate-to-severe symptoms, while at the time of the second replicate, the plant had succumbed to the infection and, as such, physiological function had ceased. In _NIT_ plants, 3-hexenal was present, whereas it was absent in \(I\) and _NINT_ palms, and Z-3-hexen-1-ol appeared to be in higher levels in _NIT_ palms compared to \(I\) and _NINT_ palms. Some of the palms (Spa_7, Spa_8, Spa_10, and Spa_21) that were classified as _NIT_ due to negative qPCR results at the time of sampling had levels of hexenal and E-2-hexanal that were comparable to \(I\) palms, and Spa_7 did not have detectable levels of 3-hexenal. These observations could be due to the fact that while these palms were actually infected with LB at the time of volatile collection, either the level of photoplasma in the palm was not detectable or the infection had not spread to the location of the palm (lower trunk) where samples were taken for qPCR analysis. Volatile emission likely initiates soon after infection and, since the infection starts in the canopy and takes time to become systemic [25], it is possible that volatiles would be indicative of infection status even if qPCR results are negative. Following the termination of the study, Spa_7 subsequently died from LB infection. This finding also is highly valuable from a management perspective because if palms can be classified as infected sooner than is possible with molecular diagnostics, it will allow for more rapid removal of infected palms, possibly before they themselves become infective and allow further spread, greatly improving management of disease's spread. The GLVs found in this work have some documented biological functions, such as aroma and flavor [26] and pathogen defense [27; 28; 29] for hexanal; herbivore defense [30; 31], plants priming [32], pathogen defense [33], and aroma and flavor [29] for E-2-hexenal; Herbivore defense [34; 35], pathogen defense [19; 36] for Z-3-hexen-1-ol; aroma and flavor [37] and pathogen defense [38] for 1-hexanol; aversive or toxic for arthropod predators for 3-hexenal and E-4-oxohex-2-nal [39]; and pathogen defense [40] for E,E-2,4 hexadienal. At all stages of host-pathogen interaction, the plant responds by releasing patterns of GLVs [34].