Exploring epigenetic variation for breeding climate resilient apple crops

Climate change with warmer winter and spring temperatures poses major challenges to apple fruit production. Long-term observations confirm the trend toward earlier flowering, which leads to an increased risk of frost damage. New breeding strategies are needed to generate cultivars that are able to stay largely unaffected by warmer temperatures. Recently, epigenetic variation has been proposed as a new resource for breeding purposes and seems suitable in principle for apple breeding. However, to serve as a new resource for apple breeding, it is necessary to clarify whether epigenetic variation can be induced by the environment, whether it can create phenotypic variation, and whether this variation is stable across generations. In this brief review, we summarize the impact of climate change on the timing of apple phenology, highlight how epigenetic variation can potentially support novel breeding strategies, and point out important features of epigenetic variation that are required for its application in breeding programs.