Antisense RhMLO1 Gene Transformation Enhances Resistance to the Powdery Mildew Pathogen in Rosa multiflora

Powdery mildew is one of the most important crop diseases worldwide. Genetic analysis has revealed that mutant alleles of the Mlo gene cause broad-spectrum resistance against pathogens found in cereal. In this study, the possibility of inducing powdery mildew (Podosphaera pannosa) resistance via transgenic technology in the rose was examined. The transgenic lines were confirmed for integration and copy number of the transgenes based on PCR and Southern blots. A clear correlation was found between resistance and the accumulation of silenced RhMLO1, based on real-time fluorescent quantitative PCR and resistance analysis. Compared with the control plants, transgenic roses displayed higher resistance levels. Furthermore, the results indicated that RhMLO1 has a negative role in the rose–powdery mildew pathogen interaction. This demonstrates the potentially viable strategy of rendering the Mlo homologs partially non-functional via a transgenic approach or mutagenesis in order to counter powdery mildew in Rosa. To the best of our knowledge, this study is one of the first attempts at using a Mlo-based resistance strategy to combat powdery mildew in Rosa.