AM fungi and P acquisition by hemiparasitic Pedicularis

Most parasitic plants do not form mycorrhizal associations and hence the nutritional role of arbuscular mycorrhizal (AM) fungi in them has not been ascertained. Using ³²P-labelling in compartmented pots, Li et al. study the facultative root hemiparasitic species Pedicularis rex and P. tricolor and find that AM colonization is low, and less than 1 % of total plant P is taken up from the soil via the AM fungus. Inoculation with AM fungi strongly interferes with P acquisition by both species from their host plant, barley, and this is almost certainly because the numbers of haustoria formed by the parasite are significantly reduced in AM plants.