Plant pigments,especially carotenoids and anthocyanins,accumulate in most fruit during ripening,and contribute to fruit color as well as human health benefits.The accumulation of these pigments often varies between cultivars.Loquat fruit accumulate carotenoids during ripening,to a different extent among cultivars.The carotenoid content and composition,mRNA levels of carotenogenic genes,as well as the number and structure of plastids in peel and flesh were compared during the development of Luoyangqing (LYQ,red-fleshed) and Baisha (BS,white-fleshed) fruit.The results suggested that the differential accumulation of carotenoids between cultivars was associated with differential expression of some carotenogenic genes.However,microscopic and ultrastructural data indicate that failure to develop normal chromoplast structures was more critically responsible for the lack of carotenoid accumulation in BS flesh.