The promoter of a pine photosynthetic gene allows expression of a beta-glucuronidase reporter gene in transgenic rice plants in a light-independent but tissue-specific manner.

In angiosperms, the expression of the cab gene that encodes the chlorophyll a/b-binding protein of PSII is light-regulated. However, the pine cab gene is expressed in a light-independent but cell-type-specific manner. In the present study, the cab-6 promoter (1.7 kbp) from pine was fused to a beta-glucuronidase (GUS) reporter gene and the chimeric gene was introduced into rice protoplasts by electroporation. The GUS expression was studied in the resultant transgenic rice plants. Expression of GUS at a substantial level was confirmed in primary leaves of dark-germinated rice seedlings, and no obvious effect of light on the GUS activity was observed. The expression of GUS was restricted to photosynthetic tissues. The pine cab-6 promoter is, thus, sufficient for induction of light-independent but cell-type-specific expression in cells of a monocot, as is the case in the original pine cells.