Progress in Studies on Plant Symbiosis Receptor-like Kinase in Nonlegumes

Most plants can form a symbiosis in root with microorganisms for mutual benefit. Nonlegumes mainly form symbiotic mycorrhiza with arbuscular fungi. The interaction is initiated by invasion of arbuscular mycorrhizal (AM) fungi into the plant root, and is followed by production of several special signal molecules, such as the symbiosis receptor-like kinase (SYMRK) from plants. SYMRK has an extracellular domain comprising three leucine-rich repeats (LRRs), a transmembrane domain and a cytoplasmic protein kinase domain. Symrk gene is required for a symbiotic signal transduction pathway from the perception of microbial signal molecules to the rapid symbiosis-related gene activation. Studies on symrk may set up a solid foundation for giving further insight into the function and mechanism of plant-fungi symbiosis.