Regulation of root morphogenesis in arbuscular mycorrhizae (Review)

Increased root branching is recognized as a general feature of arbuscular mycorrhizal (AM) roots, but a full understanding of the mechanisms involved is still lacking. Fusconi reviews the subject and concludes that fungal exudates are probably the main compounds regulating AM root morphogenesis during the first colonization steps, while a complex network of interactions governs root development in established AMs. The possible involvements of phosphate, which generally increases in AM plants, and of variations in sugar transport and in hormone homeostasis, signalling and interactions are also discussed.