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Abstract:
Induced changes in root carbohydrate pools are commonly assumed to determine
plant defoliation tolerance to herbivores. However, the regulation and species specificity
of these two traits are not well understood. We determined herbivory-induced
changes in root carbohydrates and defoliation tolerance in seven different solanaceous
plant species and correlated the induced changes in root carbohydrates and
defoliation tolerance with jasmonate inducibility. Across species, we observed strong
species-specific
variation for all measured traits. Closer inspection revealed that the
different species fell into two distinct groups: Species with a strong induced jasmonic
acid (JA) burst suffered from a reduction in root carbohydrate pools and reduced defoliation
tolerance, while species with a weak induced JA burst maintained root carbohydrate
pools and tolerated defoliation. Induced JA levels predicted carbohydrate and
regrowth responses better than jasmonoyl-L-
isoleucine
(JA-Ile)
levels. Our study
shows that induced JA signaling, root carbohydrate responses, and defoliation tolerance
are closely linked, but highly species specific, even among closely related species.
We propose that defoliation tolerance may evolve rapidly via changes in the plant’s
defense signaling network.
