Abstract
This work reports the development of suspension culture system of transgenic Marsh grapefruit (Citrus paradisi Macf., Rutaceae) callus overexpressing bacterial phytoene synthase; and the use of this suspension culture to investigate the effects of beta-cyclocitral on carotenoid content and composition. At a beta-cyclocitral concentration of 0.5 mM and after ten days cultivation, analysis of the camtenoids showed a significant increase in the content of beta-, alpha-carotene, and phytoene predominantly. The maximal increase in total provitamin A camtenoids content following beta-cyclocitral application was similar to 2-fold higher than the control, reaching 245.8 mu g/g DW. The trend for increased transcript levels of biosynthetic genes PSY and ZDS correlated with the enhancement of the content of these carotenes following beta-cyclocitral treatment and GC-MS based metabolite profiling showed significant changes of metabolite levels across intermediary metabolism. These findings suggest that beta-cyclocitral can act as a chemical elicitor, to enhance the formation of carotenes in citrus suspension-cultured cells (SCC), which could be utilized in studying the regulation of carotenoid biosynthesis and biotechnological application to the renewable production of nutritional carotenoids.