Expression of a monocot LHCP promoter in transgenic rice.

The beta-glucuronidase (GUS) gene linked to the promoter of rice light harvesting chlorophyll a/b-binding protein of photosystem II (LHCPII) was introduced into rice by electroporation. Expression of the GUS gene with the LHCP promoter in transformed protoplasts and callus was much lower than with the cauliflower mosaic virus (CaMV) 35S promoter. In green organs, however, LHCP-GUS activity with the LHCP promoter was 10-fold higher than that with the CaMV 35S promoter. Expression of the LHCP-GUS gene was detected in leaves, stems and floral organs but not in roots. Histochemical analysis of leaves showed that the GUS gene was expressed specifically in green tissues. In selfed seeds of the transformants, GUS gene expression was detectable only in the germinated embryos after greening. Northern blot analysis revealed that transcription of the GUS gene with the LHCP promoter was not detectable in dark-grown seedlings of transformants but was induced by exposure to light. These results show that regulation of the introduced chimeric gene in transgenic plants was characteristic of the LHCP gene itself.