A Prenyltransferase Gene Confirmed to Be a Carotenogenic CRTE Gene from Sweetpotato

Sweetpotato(Ipomoea batatas L.Lam.)ranks fifth among the most important food crops,after rice,wheat,maize and cassava,on a fresh-weight basis in developing countries(Scott and Maldonado,1999).Sweetpotato cultivars have white,yellow,purple or orange flesh,but only orange-fleshed sweetpotato cultivars are the rich sources of(3-carotene,which is the precursor of vitamin A(Failla et al.,2009).Accordingly,the orange-fleshed sweetpotato is the main source of(3-carotene for the people in underdeveloped coun-