Identification of New Resistance Sources From Diploid Wild Strawberry Against Powdery Mildew Pathogen

Powdery mildew pathogen causes diseases in berries and resistance breeding is hampered by the lack of sufficient sources. While control of fungal pathogens relies on chemical fungicides. In either case, a reliable source of resistance for breeding purposes is imperative for efficient protection of the crop plants. A powdery mildew isolate designated GOU1 has been identified as Podosphaera aphanis var. aphanis using light microscopy and sequencing the ITS region. Pathogenicity tests on 3 diploid wild strawberry (Fragaria vesca L.) ecotypes with GOU1 revealed 3 distinctive interaction phenotypes; enhanced susceptible (ecotype 1), intermediate susceptible (ecotype 2) and resistant (ecotype 3). In vitro staining methods with diaminobenzidine and trypan blue showed massive mycelial web and conidiophore production on the susceptible ecotype, but there was no mycelia and conidiophore production on the resistant ecotype 3. In the ecotype 3 conidiospore penetration was associated with accumulation of hydrogen peroxide production on the host cells. These findings suggest that these ecotypes could be explored as resistant gene sources to powdery mildew fungus