Evaluation of carotenoid biosynthesis, accumulation and antioxidant activities in sweetcorn (Zea mays L.) during kernel development

Summary To have a better understanding of regulatory mechanism of carotenoid accumulation in sweetcorn (Zea mays L.), we analysed carotenoid profiles, expression patterns of carotenogenic genes and antioxidant activities in two genotypes of sweetcorn during kernel development. The results suggested that the expression of carotenogenic genes played an essential role in carotenoid accumulation and higher expression levels of carotenogenic genes obviously led to higher levels of total carotenoids. It was found that the expression of upstream genes (ZmPDS, ZmZDS and ZmCRTISO) had major influence on the content of total carotenoid during kernel development. The accumulation of lycopene was closely related to the coordination of upstream and downstream genes. The expression of ZmHYD and ZmZEP was influential on zeaxanthin accumulation, which was also influenced by the rate of ZmCHYB/ZmCHYE. Expression levels of ZmCHYE were still stable in order for α-xanthophylls largely accumulated during kernel development. Lutein, zeaxanthin, α-cryptoxanthin and β-cryptoxanthin constituted the predominant carotenoids in sweetcorn. Two essential stages for carotenoid accumulation were found in sweetcorn during kernel development.