Biochemical cage match: cryptic priming of maize (Zea mays)

Priming potentially alters the dynamic of plant-herbivore interactions.  Rather than a static plant with induced defenses upon herbivory, a pseudo-induction may precede herbivore damage via an intra- or interplant signaling system.  This may provide the plant with a strategy to pre-arm itself before herbivore infestation.  Priming occurs when an undamaged plant is exposed to a primone or primogen.  The plant initiates a variety of unspecified biochemical, morphological, and perceptual changes.  When an herbivore begins to feed, the primed plant responds with greater speed and strength.  The production of green leaf volatiles (GLVs) during herbivore or mechanical damage is nearly universal in plants.  In maize (Zea mays), GLVs, the primone, trigger the primed state.  Previously, researchers established that primed maize plants produced higher jasmonic acid (JA) and volatile levels after elicitation by adding an herbivore’s regurgitant to a mechanically damaged wound site.   However, the JA and volatile response of primed maize plants to herbivory and the performance of herbivores throughout their life history remain unknown.  Preliminary bioassay data suggest that beet armyworm (BAW) Spodoptera exigua larvae fed on plants exposed to the primone, Z-3-hexenyl acetate, a GLV, exhibit delayed instar progression.  Work is in progress to establish neonate mortality rates.   BAW feeding does not appear to induce JA levels in excised primed maize tissue compared to control BAW fed tissue.  Experiments will be performed to establish JA and volatile levels in intact primed maize plants during BAW feeding.