Wheat Disease Resistance-like Gene Stimulates Susceptibility to Necrotrophic Pathogens

Disease resistance of plants is governed by genes with three protein domains. On the other hand, plant's mechanism for susceptibility is not widely-studied, especially for necrotrophic pathogens or fungi that feed on the dead cells and tissues of the host. Previous studies have shown that diseases tan spot and Stagonospora nodorum blotch on wheat produce ToxA, a toxin that stimulate susceptibility in wheat lines harboring matching toxin sensitivity gene (Tsn1).

Justin Faris of USDA Agricultural Research Service, together with other scientists, reported the cloning of Tsn1, which was found to have resistance gene-like features, including the three protein domains of the resistance genes. After inducing genetic mutation, it was revealed that all the three domains are needed for ToxA sensitivity and disease susceptibility. Tsn1 is available only in ToxA-sensitive genotypes, but Tsn1 protein is not directly stimulated by ToxA. Tsn1 transcription is strictly regulated by circadian clock and light, which suggests that the Tsn1-ToxA interactions are linked with photosynthesis pathways.

Results of the study imply that the pathogens mentioned may increase by subverting the resistance mechanisms acquired by plants to fight other pathogens.

The abstract of this study is available at http://www.pnas.org/content/107/30/13544.abstract.