Data from: Integration of two herbivore-induced plant volatiles results in synergistic effects on plant defense and resistance

Plants can use induced volatiles to detect herbivore‐ and
pathogen‐attacked neighbors and prime their defenses. Several individual
volatile priming cues have been identified, but whether plants are able to
integrate multiple cues from stress‐related volatile blends remains poorly
understood. Here, we investigated how maize plants respond to two
herbivore‐induced volatile priming cues with complementary information
content, the green leaf volatile (Z)‐3‐hexenyl acetate (HAC) and the
aromatic volatile indole. In the absence of herbivory, HAC directly
induced defense gene expression, while indole had no effect. Upon
induction by simulated herbivory, both volatiles increased jasmonate
signaling, defense gene expression and defensive secondary metabolite
production and increased plant resistance. Defenses and resistance in
dual‐volatile exposed plants were more strongly induced than in plants
exposed to single volatiles. Induced defense levels in dual
volatile‐exposed plants were significantly higher than predicted from the
added effects of the individual volatiles, with the exception of induced
plant volatile production, which showed no increase upon dual‐exposure
relative to single exposure. Thus, plants can integrate different volatile
cues into strong and specific responses that promote herbivore defense
induction and resistance. Integrating multiple volatiles may be
beneficial, as volatile blends are more reliable indicators of future
stress than single cues.

植物可通过诱导型挥发性有机物（induced volatiles）识别遭草食动物与病原体侵染的邻近植株，并启动自身防御反应。目前已鉴定出多种单一挥发性启动信号，但植物能否整合来自胁迫相关挥发性混合物的多重信号，这一问题仍未得到充分阐释。
本研究以玉米植株为实验材料，探究其对两种携带互补信息的草食动物诱导挥发性启动信号的响应——绿叶挥发性物质（green leaf volatile）(Z)-3-己烯乙酸酯（(Z)-3-hexenyl acetate，HAC）与芳香族挥发性物质吲哚（indole）。
在无草食动物取食的条件下，HAC可直接诱导防御基因表达，而吲哚未表现出显著效应。经模拟草食动物取食诱导后，两种挥发性物质均可增强茉莉酸信号通路（jasmonate signaling）活性、提升防御基因表达水平与防御性次生代谢物合成量，并显著提高植株抗虫性。
双挥发性物质暴露组植株的防御反应与抗虫性，均显著强于单一挥发性物质暴露组。双暴露组植株的诱导防御水平，显著高于两种单一挥发性物质单独作用的叠加效应；但诱导产生的挥发性物质产量除外——双暴露组与单一暴露组相比，该指标未出现显著提升。
综上，植物可整合不同挥发性信号，形成强效且特异性的防御响应，以促进草食动物防御的诱导与抗虫性提升。相较于单一信号，挥发性混合物可作为更可靠的未来胁迫预警指标，因此整合多种挥发性信号或对植物具有进化优势。