Chlorphyll a/b Binding Proteins and the Small Subunit of Ribulose Bisphosphate Carboxylase are Encoded by Multiple Genes in Petunia

Summary

There are at least sixteen chorophyll a/b binding protein coding sequences in the nuclear genome of the diploidized Mitchell haploid Petunia line. These genes can be classified into at least five distinct families based on the relatedness of the nucleotide sequence which encodes the 60, C-terminal amino acids of the peptide. There is as much as 10% nucleotide divergence and 5% amino acid sequence divergence between the genes of different families in this region. For two of the families we find that two closely related genes are adjacent and in both examples the two genes are in an inverted orientation with respect to each other such that the 5′ ends of the genes are opposed. At least one gene from four of the families is transcribed. The 3′ untranslated sequences of the genes are divergent between families yet well conserved within a single family.

The multiple genes for the small subunit peptide of ribulose (-1,5-) bisphosphate carboxylase (SSU) can be also be divided into four families based on the relatedness of the coding sequences. We have found evidence for linkage between two SSU genes and for the transcription of at least one gene from each family.

Our data suggest that there may be at least five different chlorophyll a/b binding peptides, and four different small subunit peptides for ribulose (-1,5-) bisphosphate carboxylase in the petunia leaf chloroplast.