Genome Expression during Normal Leaf Development

Abstract

The quantitative relationships between ribulose bisphosphate carboxylase [RuBPase], nuclear ploidy and plastid DNA content were examined in the nonisogenic polyploid series Triticum monococcum (2X), T. dicoccum (4X) and T. aestivum (6X). RuBPase per mesophyll cell (pigs) to nuclear DNA per mesophyll cell (pigs) were almost identical in the 3 spp. RuBPase per plastid was 14.1, 14.7 and 16.8 pigs in the 2X, 4X and 6X ploidy levels, respectively. Plastid area in these 3 spp. decreased with increasing nuclear ploidy so the concentration of RbBPase in the plastoids was 60% higher in the hexaploid compared to the diploid species. DNA levels per plastid were 64 and 67 fg for the diploid and tetraploid species, respectively, but were 40% less in the plastids of the hexaploid species. These relationships are discussed in terms of cellular and plastid control of RuBPase content.