Abstract: Carotenoid compounds in the fruit pulp of somatic hybrid [‘Bonnaza’naval orange（Citrus sinensis Osbeck）+ rough lemon（C. jambhiri Lush）]and both parental species were quantitatively evaluated by HPLC，sugars and organic acids content were investigated by GC，and Real-time RT-PCR was used to detect expression levels of key genes involved in the carotenoid，sugars and organic acids biosynthetic pathways. Results revealed that strong dominance of rough lemon was found for citric acid，malic acid and carotenoid compound in somatic hybrid fruit，while sucrose content showed mid-parent value. Gene expression was higher in navel orange than in rough lemon for four of seven genes analyzed involved in carotenoid biosynthetic pathway. Rough lemon dominance was observed for expression of CitCrt，CitLcy-e and CitZep. These results indicated that rough lemon played a dominant role in inheritance of fruit quality characteristics and gene expression in the somatic hybrid.

Key words: Citrus, somatic hybrid, carotenoid, sugar, organic acid