Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2013
Publication Date: N/A
Technical Abstract: Blue mold caused by Penicillium expansum is the most destructive pathogen of stored apples in the US and worldwide. It was recently shown that resistance to blue mold exists in wild apples, Malus sieversii, from Kazakhstan and central Asia maintained in a germplasm collection in Geneva, NY. We initiated studies to determine the mechanism of resistance to P. expansum in select wild apple accessions. Wound responses (up to 96 h in 24 h intervals), affecting P. expansum infection and related cytological changes, were observed in accessions with varying resistance levels. In general; the more resistant the accession,the quicker the wound response that prevented fungus from infecting tissue and causing decay. On moderately resistant accessions, a 24 h interval between wounding and inoculation was sufficient to avert decay. More time was needed for the wounds to develop resistance to higher inoculum concentrations of the pathogen. No decay developed on immune apple accessions, even when inoculated immediately after wounding. Reactive oxygen species (ROS) were detected at high levels immediately after wounding in the immune accessions, and gradually accumulated around the wound over time, in both resistant and moderately resistant accessions. Results from this study suggest an involvement of ROS in the mechanism of resistance to P. expansum in select wild apple accessions.