Abstract: The gene expression，protein accumulation and subcellular localization of Chalcone isomerase（CHI，EC 5.5.1.6）in developing grape berry（Vitis vinifera L.‘Cabernet Sauvignon’）was performed via RT-PCR，Western-blotting and immunogold electron microscopy technique using grape CHI antibody. The results showed that the quantity of CHI gene transcript and protein in developing grape berry was developmental stage dependant. The high content of CHI transcripts and protein was observed in grape berries at early development stage（20 days after flower）and veraison，corresponding well to the accumulation of total flavonoids. Immunogold localization result showed that CHI was mainly localized in cytoplasm of the young grape berry skin cells，while some gold particles representing CHI were also found in the vacuole and plastid. In the skin cells of grape berry at veraison，CHI was mainly distributed in cytoplasm，plastids and nuclear，and the gold particles representing CHI increased significantly at this stage；CHI were observed in cytoplasm at late developmental stage，a little was also investigated in the vacuole and plastids.

Key words: grape, chalcone isomerase, flavonoid, subcellular localization