Neutral lipid fatty acid analysis is a sensitive marker for quantitative estimation of arbuscular mycorrhizal fungi in agricultural soil with crops of different mycotrophy

The impact of host mycotrophy on arbuscular mycorrhizal fungal (AMF) markers was studied in a temperate agricultural soil cropped with mycorrhizal barley, flax, reed canary-grass, timothy, caraway and quinoa and non-mycorrhizal buckwheat, dyer’s woad, nettle and false flax. The percentage of AMF root colonization, the numbers of infective propagules by the Most Probable Number (MPN) method, and the amounts of signature Phospholipid Fatty Acid (PLFA) 16:1ω5 and Neutral Lipid Fatty Acid (NLFA) 16:1ω5 were measured as AMF markers. Crop had a significant impact on MPN levels of AMF, on NLFA 16:1ω5 levels in bulk and rhizosphere soil and on PLFA 16:1ω5 levels in rhizosphere soil. Reed canary-grass induced the highest levels of AMF markers. Mycorrhizal markers were at low levels in all non-mycorrhizal crops. NLFA 16:1ω5 and the ratio of NLFA to PLFA 16:1ω5 from bulk soil are adequate methods as indicators of AMF biomass in soil.