Carotenoids are the main pigments of ripe red-fleshed loquat fruit; however, only extremely low amount of carotenoids is present in flesh tissue of ripe white-fleshed loquats. To investigate the mechanism leading to the diversity of carotenoid patterns in red- and white-fleshed cultivars, expression patterns of carotenogenic genes and the subcellular structure of plastid in fruit of Luoyangqing (LYQ, red-fleshed) and Baisha (BS, white-fleshed) loquats were studied. This research has been published in the Journal of Experimental Botany (2012, 63, 341-254), entitled “Plastid structure and carotenogenic gene expression in red- and white- fleshed loquat (Eriobotrya japonica) fruits”. Ph.D student Xiumin Fu is the first author of this paper and Professor Changjie Xu is the corresponding author. This research was supported by the National Natural Science Foundation in China.
The mRNA levels of 15 carotenogenesis-related genes were analysed during fruit development and ripening. The expression patterns of PSY1, CYCB and BCH might be responsible for the carotenoid accumulation of the flesh of LYQ when ripe. However, these genes showed similar expression patterns in the flesh of BS. The carotenogenic gene expression seemed insufficient to explain the big difference in carotenoid content between the two cultivars. Normal chromoplasts structure was found in the flesh of LYQ cultivar at the ripe stage. However, no chromoplast structure was found in the cells of fully ripe BS fruit flesh, which suggested that the failure to develop normal chromoplasts in BS flesh might be related to the lack of carotenoid accumulation.
