Carotenoid isomerase (CRTISO) catalyzes the isomerization of prolycopene to all-trans-lycopene in the carotenoid biosynthetic pathway. We isolated two full-length cDNA gene, CuCRTISO and CuCRTISO-like, from Citrus unshiu. To confirm whether these two genes have the function of the carotenoid isomerase, The full-length cDNA of CuCRTISO and CuCRTISO-like gene, respectively, were fused with 35S promoter and NOS terminal region and then transformed into tomato CRTISO mutant, Tangerine, which shows orange fruit due to lack of carotenoid isomerase activity. The mature fruit color of the transgenic line expressing CuCRTISO gene changed from orange to red, which was similar to the fruit color of the tomato “Money Maker”. We also carried out HPLC analysis to detect all-trans lycopene, which is produced from prolycopene by carotenoid isomerase. In the transgenic line expressing CuCRTISO the all trans lycopene was detected from mature fruit but in the tangerine mutant several prolycopenes were detected from it. On the other hand, the transgenic line expression of CuCRTISO gene retained the orange-color fruit at the mature stage as Tangerine mutant. These studies indicate that the CuCRTISO gene has a function of carotenoid isomerase and also plays a role of it in other plant species, and that the CuCRTISO-like gene might be not enough to produce the all trans lycopene or has a another unknown function(s).

• Chang-Ho Eun(Subtropical Horticulture Research Institute, Jeju National University) Corresponding Author
• In-Jung Kim(Subtropical Horticulture Research Institute, Jeju National University, Faculty of Biotechnology, College of Applied Life Sciences & Research Institute for Subtropical Agriculture and Biotechnology, SARI, Jeju National University)