Despite the growing body of studies demonstrating that herbivore-induced plant volatiles (HIPV) induce and prime receiver plant defences, few studies have investigated the effect of HIPVs on primary metabolism of receiver plants and whether responses to HIPVs are consistent across wild and cultivated plant varieties. Here we investigated the effect of HIPVs on net photosynthesis, stomatal conductance, volatile emissions, and number of eggs laid by female Plutella xylostella on receiver plants in two wild and two cultivated Brassica rapa varieties. Plants responded to exposure to HIPVs by increasing their net photosynthesis and stomatal conductance. Responses were clearest in two varieties i.e., Cordelia and a wild Moroccan population, for which exposure to HIPVs also reduced their susceptibility to oviposition but did not alter volatile emissions. The results constitute an advance to research on plant-plant interactions by showing that exposure to HIPVs can promote plant primary metabolism by increasing photosynthesis as a probable mechanism to compensate for costs of induced defences. The results also suggest that responses to HIPVs is maintained across wild and cultivated plants but varies among varieties, and that the traits responsible for effective plant-plant interaction might not have been affected by breeding.

Data were collected between the 14 October 2020 to 30 March 2021 in laboratories of the Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio FIN-70211, Finland.