Expression pattern of UidA gene under the control of rice glutelin GluA-2 gene upstream sequence in transgenic rice endosperm.

In order to study the expression pattern of rice glutelin endosperm specific promoter in Chinese cultivar Zhonghua 8 (Oryza sativa L. subsp japonica), UidA gene was fused with rice glutelin GluA-2 gene 5' upstream sequence 2.3 kb and 750 bp upstream respectively and transferred into rice by Agrobacterium mediated transformation. Southern blot indicated that UidA gene was integrated into the genome of transgenic plants as single copy. Northern blot demonstrated that the expression of UidA gene and endogenous GluA-2 gene reached their highest level at 13-15 days and 11-13 days after pollination respectively, and then declined. Histochemical staining of immature transgenic rice seeds showed UidA gene was specifically expressed in endosperm and the highest level GUS expression was observed in aleurone layer. Quantitative analysis of GUS activity showed seeds GUS activity of that 2.3 kb transgenic plant was about two to three folds of those of 750 bp transgenic plant. Sequence analysis suggested that the G-box located in the -2,170 bp (from transcription start site) may be a quantitative cis-element.