Abstract

Arbuscular mycorrhiza (AM) is an ancient symbiosis between plants and glomeromycotan fungi that is extremely widespread in the plant kingdom and is based on nutritional benefits to both symbiotic partners. The plant receives mineral nutrients, especially phosphate from the fungus and in return provides the fungus with carbohydrates and lipids. As a result, AM can significantly increase plant growth in low nutrient soils. For symbiosis establishment AM fungi colonize the root interior. This involves distinct and genetically separable developmental steps that are largely under plant control. They include drastic plant cell rearrangements that precede differentiation of fungal hyphae into particular shapes inside plant cells. We are interested in the plant molecular mechanisms required for initiation of AM symbiosis and for the rearrangement of root cortex cells allowing formation of highly-branched fungal arbuscules, which mediate nutrient exchange. In addition, we work towards elucidating the genetic determinants of AM-mediated plant growth increase. Recent progress in our understanding of AM development and function will be presented.