Marker-assisted seedling selections in sour cherry for cherry leaf spot resistance and fruit flesh color

Michigan is the leading producer of sour cherry ( Prunus cerasus L.) in the United States (U.S.), and 'Montmorency' is the major sour cherry variety grown. This cultivar has high fruit production and bright red skin color that is the basis of the brilliant red color characteristic of cherry pie. Despite those superior qualities, 'Montmorency' is highly susceptible to the cherry leaf spot (CLS) fungus. The goal of the Michigan State University sour cherry breeding program is to develop new cultivars that have fruit with the characteristic 'Montmorency' color and are also disease resistant. Breeding new sour cherry cultivars is expensive due to the long generation time and the high expense of planting and evaluating seedlings in the field. The objective of this study was to implement and evaluate the impact of marker-assisted seedling selection (MASS) for fruit flesh color and CLS resistance in seedlings generated from crosses in 2013 using available DNA diagnostic tests. Implementation of a diagnostic DNA test for CLS resistance resulted in the elimination of the majority of seedlings predicted to be CLS susceptible prior to field planting. Implementation of a diagnostic DNA test for fruit flesh color resulted in the elimination of approximately half of the seedlings prior to field planting. The phenotypes of the original progeny individuals and the remaining progeny were predicted to demonstrate the expected gain from selection with the use of these two DNA tests.