Tissue-specific and light-regulated expression of a pea nuclear gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase.

We have examined the expression of a member of the multigene family encoding the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase in various tissues of pea. The rbcS gene, pPS-2.4, was characterized by DNA sequence analysis and 5' and 3' end mapping of its mRNA transcript. rbcS polypeptides were shown to be differentially present in various tissues of light- and dark-grown plants. Northern analysis shows that compared with green leaves, the level of rbcS mRNA is reduced to approximately 50% in pericarps, 8% in petals and seeds, and 1-3% in etiolated leaves, stems, and roots. 5' S1 nuclease mapping of total rbcS mRNA was used to quantitate the relative amount of pPS-2.4 gene-specific transcripts in each tissue. pPS-2.4 mRNA accounts for approximately 30-35% of total rbcS transcripts in green leaves, but only 5-10% in pericarps, 15-20% in seeds, and is below detection in petals and etiolated leaves. We conclude that the pPS-2.4 gene is expressed in a tissue-specific, light-regulated fashion and that transcriptional controls of individual rbcS genes vary.