Aphid acceptance of barley exposed to volatile phytochemicalsuddiffers between plants exposed in daylight and darkness

摘要

It is well known that volatile cues from damaged plants may induce resistance inudneighboring plants. Much less is known about the effects of volatile interaction betweenudundamaged plants. In this study, barley plants, Hordeum vulgare cv. Kara, were exposedudto volatiles from undamaged plants of barley cv. Alva or thistle Cirsium vulgare, andudto the volatile phytochemicals, methyl salicylate or methyl jasmonate. Exposures wereudmade either during natural daylight or darkness. Acceptance of exposed plants by theudaphid Rhopalosiphum padi was assessed, as well as the expression of putative markerudgenes for the different treatments. Aphid acceptance of plants exposed to either barley orudC. vulgare was significantly reduced, and an effect of the volatiles from undamagedudplants was confirmed by the induction of pathogenesis‑related protein, PR1a in exposedudplants. However the effect on aphid acceptance was seen only when plants were exposedudduring darkness, whereas PR1a was induced only after treatment during daylight. Aphidudacceptance of plants exposed to either methyl salicylate or methyl jasmonate was significantlyudreduced, but only when plants were exposed to the chemicals during daylight.udAOS2 (allene oxide synthase) was induced by methyl jasmonate and BCI‑4 (barleyudchemical inducible gene‑4) by methyl salicylate in both daylight and darkness. It isudconcluded that (a) the effects on aphids of exposing barley to volatile phytochemicals wasudinfluenced by