ABSTRACT
Nutritional content is the next frontier for fruit breeders. Increased awareness of the contribution diet makes to long-term health has prompted geneticists and breeders to extend the historic foci of eating quality (texture and flavor), appearance (shape, color, pattern, and size), storability, and pest and disease resistance (Laurens, 1999; Khanizadeh et al., 2007a,b; Yoo et al., 2007; Shukla and Mattoo, 2009; Szankowski et al., 2009; Watkins and Liu, 2011; Davies and Espley, 2013). Bioactive phytochemicals, often termed “antioxidants,” have drawn much interest due to the explosion in evidence for a role in preventing major chronic diseases, including cardiovascular diseases, cancers, and type 2 diabetes. Flavonoids feature highly in these studies. While much of the evidence has come from epidemiological studies, and others have used isolated chemicals in clinical trials, the prevailing view is that the benefits come from the synergistic effects of the many compounds within the whole food (Liu, 2003). This is an important feature for horticulture and for the potential to improve dietary health of the more self-sufficient societies of low-income and developing countries—which incidentally are those at greatest risk of diet-related diseases such as cardiovascular disease (Beaglehole and Bonita, 2008; World Health Organization, 2010; Kim and Johnston, 2011). For these reasons, plus their wide international consumption, relatively long storage life, and the richness of particular flavonoids, apples are the major focus of this review.
