Functional analysis of the Arabidopsis thaliana Mlo (AtMlo) gene family
Final Report Abstract
The goal of this project was to characterize in detail the broad-spectrum powdery mildew resistance conferred by loss-of-function alleles of AtMLO2. We found that the developmentally controlled pleiotropic phenotypes of barley mlo mutants also occur in Atmlo2 mutants, suggesting a conserved function of the proteins as negative regulators of leaf senescence. By genetic epistasis analysis we discovered that powdery mildew resistance in Atmlo2 functions independently of the well-known defence signalling molecules salicylic acid, ethylene and jasmonic acid. Nevertheless, salicylic acid spontaneously hyper-accumulates in Atmlo2 mutants during development, and this accumulation coincides with the onset of pleiotropic phenotypes, suggesting that their occurrence is dependent on salicylic acid. Double mutants in Atmlo2 and genes of the salicylic acid biosynthesis/signalling pathway indeed do not show the pleiotropic phenotypes. We demonstrate that AtPEN1, AtPEN2 and AtPEN3, three genes required for effective pre-invasive defence against non-adapted powdery mildew pathogens, are each also required for Atmlo2-conditioned resistance against the adapted powdery mildew pathogen. We analyzed in yeast the interaction between AtMLO2 and t-SNARE (syntaxin) proteins to investigate isoform-specificity and structural requirements of this protein-protein interaction.
Publications
- 2006. Conserved requirement for a plant host cell protein in powdery mildew pathogenesis. Nature Genetics 38: 716-720
Consonni, C., Humphry, M. E., Hartmann, H. A., Livaja, M., Durner, J., Westphal, L., Vogel, J., Lipka, V., Schulze-Lefert, P., Somerville, S. C., and Panstruga, R.
- 2006. mlo-based powdery mildew immunity: Silver bullet or simply non-host resistance? Molecular Plant Pathology 7: 605-610
Humphry, M., Consonni, C , and Panstruga, R.
