Calmodulin interacts with MLO protein to regulate defence against mildew in barley

• Published in: Nature (London) 2002-03, Vol.416 (6879), p.447-451
• Main Authors: Cho, Moo J, Schulze-Lefert, Paul, Kim, Min C, Panstruga, Ralph, Elliott, Candace, Müller, Judith, Devoto, Alessandra, Yoon, Hae W, Park, Hyeong C
• Format: Article
• Language: English
• Subjects: Agriculture; Agronomy. Soil science and plant productions; Airborne microorganisms; Ascomycota - physiology; Barley; Biological and medical sciences; Blumeria graminis; Blumeria graminis hordei; Calcium - metabolism; Calmodulin - metabolism; Calmodulin - physiology; Cloning, Molecular; Flowers & plants; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fungi; Gene Expression Regulation, Plant; Gene Silencing; Genetic Complementation Test; Genetics; Genetics and breeding of economic plants; Grain; Hordeum - genetics; Hordeum - microbiology; Hordeum - physiology; Hordeum vulgare; Humanities and Social Sciences; letter; MLO protein; multidisciplinary; Mutation; Pathogens; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Pest resistance; Phytopathology. Animal pests. Plant and forest protection; Plant pathogens; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins - physiology; Protein Binding; Protein Structure, Tertiary; Proteins; Science; Science (multidisciplinary); Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/416447a

In plants, defence against specific isolates of a pathogen can be triggered by the presence of a corresponding race-specific resistance gene, whereas resistance of a more broad-spectrum nature can result from recessive, presumably loss-of-regulatory-function, mutations. An example of the latter are mlo mutations in barley, which have been successful in agriculture for the control of powdery mildew fungus (Blumeria graminis f. sp. hordei; Bgh). MLO protein resides in the plasma membrane, has seven transmembrane domains, and is the prototype of a sequence-diversified family unique to plants, reminiscent of the seven-transmembrane receptors in fungi and animals. In animals, these are known as G-protein-coupled receptors and exist in three main families, lacking sequence similarity, that are thought to be an example of molecular convergence. MLO seems to function independently of heterotrimeric G proteins. We have identified a domain in MLO that mediates a Ca2+-dependent interaction with calmodulin in vitro. Loss of calmodulin binding halves the ability of MLO to negatively regulate defence against powdery mildew in vivo. We propose a sensor role for MLO in the modulation of defence reactions.