Part 1 Interactions in rhizosphere: section summary; mycorrhiza-microbe interactions - effect on rhizosphere; interactions between arbuscular mycorrhizal fungi and non-symbiotic beneficial microbiota; interaction of arbuscular mycorrhiza with nitrogen-fixing bacteria; arbuscular-mycorrhiza and plant disease. Part 2 Interactions in soil: section summary; influence of edaphic and enviromental factors on arbuscular mycorrhizae; influence of adverse soil conditions on the formation and function of arbuscular mycorrhiza; arbuscular mycorrhizae - mineral nutrient and water acquisition; possible role of arbuscular mycorrhizal fungi in development of soil structure. Part 3 Interactions in plants: section summary; plant and fungal responses to colonization; cellular and molecular aspects; specificity and compatibility in arbuscular mycorrhizal symbiosis; physiology of nutrient uptake by arbuscular mycorrhizal fungi.