“…The “candidate gene approach” has been used in QTL or association mapping to test SNPs within a candidate gene for a significant association with the yellow color character. Although most studies were focused in increasing the carotenoid content or altering the relative components through conventional breeding (Schulthess and Schwember, 2013), some carotenoid genes have been characterized and/or linked to QTL for carotenoids. In wheat, significant attention has been given to the carotenoid biosynthesis genes ( PSY (Pozniak et al, 2007; He et al, 2008; Dibari et al, 2012; Campos et al, 2016; Vargas et al, 2016), lycopene ε-cyclase ( LCYE ) (Howitt et al, 2009; Crawford and Francki, 2013), lycopene β-cyclase ( LYCB ) (Zeng et al, 2015), carotenoid β-hydroxylase ( HYD ) (Qin et al, 2012), carotene desaturase ( PDS ), and ZDS (Cong et al, 2010), while the degradation of carotenoids has been studied by some catabolic genes, such as aldehyde oxidase ( AO ) (Colasuonno et al, 2017b), polyphenol oxidase ( PPO ) (Si et al, 2012), lipoxygenase ( LOX or LPX ) (Verlotta et al, 2010), and peroxidase ( PER ) (Asins and Perez de la Vega, 1985; Fraignier et al, 2000; Ficco et al, 2014).…”