Developmental regulation of two genes encoding ribulose-bisphosphate carboxylase small subunit in pea and transgenic petunia plants: Phytochrome response and blue-light induction.

We describe the effects of light quality on the light-induced expression of two genes (rbcS-3A and rbcS-3C) encoding the ribulose-1,5-bisphosphate carboxylase small subunit of pea plants. These two genes exhibit distinctive photoresponses depending on the developmental stages of the leaves. In etiolated primary leaves, changes in the rbcS-3A and rbcS-3C transcript levels are regulated by phytochrome. In mature green leaves, on the other hand, the transcript levels are modulated by a putative blue-light photoreceptor working in concert with phytochrome. We transferred the two pea rbcS genes into the petunia genome and found that their phytochrome (rbcS-3A and -3C) and blue-light responses (rbcS-3C) are recapitulated in the appropriate developmental stages of the transgenic plants. Moreover, the transgenic plants express the pea rbcS genes in leaves at levels close to those in pea leaves. Our results show that 0.4 kilobases of the rbcS-3A and 2 kilobases of the rbcS-3C upstream regions are sufficient for these photoresponses.