Dicke M

Onkokesung N

Reichelt M

Schuurink RC

vanDoorn A

Plants respond to herbivory with the induction of resistance, mediated by distinct phytohormonal signaling pathways and their interactions. Phloem feeders are known to induce plant resistance via the salicylic acid (SA) pathway whereas biting-chewing herbivores induce plant resistance mainly via the jasmonate (JA) pathway. Here, we show that a specialist caterpillar (biting-chewing herbivore) and a specialist aphid (phloem feeder) differentially induce resistance against Pieris brassicae caterpillars in Arabidopsis thaliana plants. Caterpillar feeding induces resistance through the JA signaling pathway that is associated with the induction of kaempferol 3,7-dirhamnoside, whereas aphid feeding induces resistance via a novel mechanism involving sinapoyl malate. The role of sinapoyl malate is confirmed through the use of a mutant compromised in the biosynthesis of this compound. Caterpillar-induced resistance is associated with a lower cost in terms of plant growth reduction than aphid-induced resistance. A strong constitutive resistance against P. brassicae caterpillars in combination with a strong growth attenuation in plants of a T-DNA insertion mutant of WRKY70 (wrky70) suggest that the WRKY70 transcription factor, a regulator of downstream responses mediated by JA-SA signaling crosstalk, is involved in the negative regulation of caterpillar resistance and in trade-off between growth and defense. In conclusion, different mechanisms of herbivore-induced resistance come with different costs and a functional WRKY70 transcription factor is required for the induction of low-cost resistance

Differential Costs of Two Distinct Resistance Mechanisms Induced by Different Herbivore Species in Arabidopsis

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