P-412 - Identification and characterization of new factors regulating arbuscule collapse

Arbuscular mycorrhiza (AM) is an ancient symbiosis between the majority of land plants and fungi of the Glomeromycotina. This mutualistic association provides plants with water and minerals in exchange for sugars and lipids. At the centre of the symbiosis are branched tree-shaped fungal structures, arbuscules, that develop in inner cortex cells of the root. Arbuscule development is dynamic and regulated by the plant in accordance with its physiological state. Arbuscules have a lifetime of 2 to 5 days, after which they collapse. Although regulators influencing arbuscule formation are known, little is known about the regulation of their degeneration. In Lotus japonicus, transcription factor MYB1 regulates this process by inducing the expression of genes encoding hydrolytic enzymes.
Arbuscule collapse may be induced by a variety of reasons, such as avoiding fungal parasitism or inefficiency in nutrient delivery. To better understand this, we use MYB1 as a starting point to identify additional regulators and executors of arbuscule collapse in Lotus japonicus. We aim to identify MYB1 interacting proteins and downstream target genes and to characterize their functions. Results from this work will start to fill major knowledge gaps on the dynamic developmental regulation of central structures within one of the most widespread symbioses on Earth.