Pathogen-induced MdWRKY1 in ‘Qinguan’ Apple Enhances Disease Resistance

The WRKY transcription factors have important functions in plant-defense signalling networks. We isolated MdWRKY1 from the Chinese ‘Qinguan’ apple, which is resistant to Alternaria blotch or leaf spot. The MdWRKY1 protein was targeted to the nucleus and activated the expression of a reporter gene, consistent with the functioning of a transcription factor. When plants were infected with the pathogen Alternaria alternata f. sp. mali, MdWRKY1 was induced dramatically. Similarly, treatment with hormones SA and MeJA increased transcription significantly. Overexpression in tobacco also enhanced resistance to Phytophthora parasitica var. nicotianae Tucker. These results suggest that MdWRKY1 is a positive regulator of the defense response in higher plants.