Seed-Specific Expression of a Rice Prolamin RP3/GUS Chimeric Gene in Nicotians tabacum cv. Wisconsin 38

The promoter region of a rice prolamin RP3 isolated from Oryza sativa cv. Tainung 67 was fused with bacterial ß-D-glucuronidase (GUS) structural gene and expressed in tobacco (Nicotiana tabacum cv. W38). A significantly higher GUS activity was found in seeds than any other tissues of transgenic regenerants. The data suggest a seed-specific expression of the rice RP3 promoter in tobacco. The GUS activity in seeds appeared 6 days after flowering (DAP), and continued to increase and reached the maximum from 9 to 15 DAF. Unlike the endosperm-specific expression of the prolamin promoter/GUS chimeric gene reported by Zhou and Fan (1993) in transgenic tobacco seeds, RP3 promoter/GUS chimeric gene was induced in both embryo and endosperm tissues. The GUS activity could also be inherited to T2 seeds of transgenic T1 progeny plants. Based on these data we conclude that the rice prolamin RP3 promoter can drive a seed-specific expression in tobacco.