Phytochemicals and spore germination: At the root of AMF host preference?

Plants trigger various responses in the organisms living around them using a wide array of phytochemicals, which are components of their adaptation to a biological environment. The roots of five varieties of chickpea inoculated with Glomus intraradices were extracted, and extracts were fractionated, first based on solubility in methanol and further by HPLC. We found a relationship between chickpea genotype and root phytochemical composition. Several HPLC fractions repressed the germination of AM fungal spores in bioassays conducted in multi-well plates with extracts from the variety CDC Anna. This repression may be an expression of the control of the plant on the AM fungal symbionts. Glomus etunicatum and Gigaspora rosea spore germination responded differently to exposure to the HPLC fractions soluble in 25% methanol. A differential response of AM fungal species to plant phytochemicals could be involved in the so called host preference of AM fungi. Whereas extensin and other proteins were identified in a bioactive root extract fraction, other proteins undetected by LC-MS/MS analysis and non-peptidic compounds may be involved in AMF spore germination suppression. (C) 2012 Elsevier B.V. All rights reserved.