Mildew resistance locus o (MLO) proteins are plant-specific seven-transmembrane (7TM) proteins that are thought to play a role in vesicle trafficking to the plasma membrane. Certain members of the MLO gene family are required for powdery mildew (PM) fungi (Erysiphales) to establish a pathogenic interaction with their plant hosts. Such MLO genes increase in transcription in response to PM infection, and the loss of their function confers broad-spectrum resistance to PM pathogens in barley, tomato, and Arabidopsis thaliana. In this study, a 17-member MLO gene family has been identified in the genome sequence of Vitis vinifera. Fourteen genes of the VvMLO family have been shown to be transcribed at various levels in shoot tips, flower buds, flowers, and leaves. Two VvMLOs increased in transcription in response to the grapevine-adapted PM fungus Erysiphe necator. The predicted polypeptides encoded by these two PM-responsive VvMLOs clustered in the same phylogenetic clade as AtMLO2, AtMLO6, and AtMLO12, proteins that are required by the PM fungus Golovinomyces orontii for causing disease on A. thaliana. The PM-responsiveness of these grapevine genes and their relatedness to AtMLOs suggest that a grapevine MLO gene (or genes) may also be involved in the pathogenesis of E. necator.
- Copyright © 2008 by the American Society for Enology and Viticulture