Plant chemical defense induced by a seed-eating pollinator mutualist.
Plant-seed parasite pollination mutualisms involve a specific pollinator whose larvae develop by consuming a fraction of the host plant seeds. These mutualisms are stable only if the plant can control seed destruction by the larvae. Here, we studied the chemical response of the European globeflower Trollius europaeus to infestation by an increasing number of Chiastocheta fly larvae. We used liquid chromatographic analysis to compare the content of phenolic compounds in unparasitized and parasitized fruits collected in two natural populations of the French Alps, and mass spectrometry and nuclear magnetic resonance to elucidate the structure of adonivernith, a C-glycosyl-flavone. This compound is present in many of the organs of T. europaeus, but not found in other Trollius species. Furthermore, it is overproduced in the carpel walls of parasitized fruits, and this induced response to infestation by fly larvae is density-dependent (increases with larval number), and site-dependent (more pronounced in the high-altitude site). Mechanical damage did not induce adonivernith production. This tissue-specific and density-dependent response of T. europaeus to infestation by Chiastocheta larvae might be an efficient regulation mechanism of seed-predator mutualist population growth if it decreases survival or growth of the larvae.
Gallet
Christiane
C
Laboratory of Alpine Ecology (TDE) UMR CNRS 5553, University of Savoie, 73376, Bourget-du-lac, France. christiane.gallet@univ-savoie.fr
Ibanez
Sebastien
S
Zinger
Lucie
L
Taravel
François R
FR
Trierweiler
Michel
M
Jeacomine
Isabelle
I
Despres
Laurence
L
D000818:Animals; D004175:Diptera / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005638:Fruit; D007814:Larva; D010636:Phenols / Q000378:metabolism; D011058:Pollen; D029626:Ranunculaceae / Q000378:metabolism*; D012098:Reproduction; D012639:Seeds; D013559:Symbiosis
D010636:Phenols