VARIATION OF SULFORAPHANE LEVELS IN BROCCOLI (BRASSICA OLERACEA VAR. ITALICA) DURING FLOWER DEVELOPMENT AND THE ROLE OF GENE AOP2

Sulforaphane is abundant in broccoli (Brassica oleracea var. italica) and has been widely studied since it may reduce the risk of several types of cancer. Here, the variation of sulforaphane levels during different stages of broccoli flower bud development was studied by high-performance liquid chromatography (HPLC). At the same time, the expressions of gene AOP2in all the materials were studied by real-time Polymerase chain reaction (RT-PCR), and the purpose was to reveal the correlation of AOP2 and sulforaphane contents in different organs of broccoli flower bud development. Sulforaphane levels were evaluated in broccoli florets, buds in bolting, flowers, and ripe seed. The results showed that there was a good linear equation, Y=3754.22X-2072.47, R (2)=0.9991, and sulforaphane levels increased during development from florets to young buds in bolting plants, thereafter decreased gradually in older buds to flowers. The ripe seed was the highest organ (13.35g/kg DW (dry weight)) with sulforaphane content in all the materials. RT-PCR result showed an opposite relationship of sulforaphane contents and the expression levels of gene AOP2 from young buds to flowers in bolting period. The study demonstrated that the over-expression of the gene AOP2 leads to a peak level of sulforaphane content in organs of broccoli.