To investigate the molecular changes that might have occurred in genes for @entity2388 , @entity6546 dikinase ( @entity70343 ) during the evolution of C4 plants from C3 plants, we isolated a full-length cDNA and the corresponding gene for a C4-like @entity70343 from @entity579 , a C3 gramineous plant and compared their structures and promoter activities to those of the corresponding gene from @entity2829 , a C4 gramineous plant. As in @entity2829 , there are at least two @entity70343 genes in @entity579 and one of them was very similar to the @entity2829 C4-type @entity70343 . The deduced @entity535 sequence of the @entity579 @entity70343 was 88% homologous to the @entity2829 C4-type @entity70343 in the mature peptide region and 56% homologous in the transit peptide region. The C4-like @entity70343 in @entity579 contained 21 exons, which were interrupted by twenty introns, and the positions of the introns were essentially the same as those in the gene from @entity2829 , with the except in that the gene from @entity579 had two extra introns. Such extra introns were also found in the C4-type @entity70343 from a dicot, Flaveria, at the same positions. These results strongly suggest that the two introns were present in an ancestral gene before the divergence of monocot and dicot plants. The C4-like @entity70343 in @entity579 contained two functionally independent promoters had generated a larger transcript with the transit peptide region and a smaller transcript without this region. The unusual dual-promoter system for transcription has been conserved in the C4-type @entity70343 gene from @entity2829 , indicating that the dual-promoter system is a common feature of @entity70343 genes in both C3 and C4 plants. The patterns of expression of the two transcripts in @entity579 were different: the larger transcript was expressed exclusively in green leaves at a low level whereas the smaller transcript was expressed in some reproductive organs at a high level. Essentially the same patterns of expression were observed in @entity2829 , but the level of expression of the larger transcript in @entity2829 green leaves was much higher than that in green leaves of @entity579 . The promoter activities of the @entity579 and @entity2829 genes for @entity70343 were examined directly in a transient expression assay in @entity2829 mesophyll protoplasts after electroporation with promoter::beta-glucuronidase chimeric genes. The @entity579 promoter for the smaller transcript was very active in the protoplasts but the @entity579 promoter for the larger transcript had relatively low activity. By contrast, both promoters of the @entity2829 gene had high activity. Taken together, these results demonstrate that the @entity579 C4-like @entity70343 is very similar to the @entity2829 C4-type @entity70343 , not only in terms of primary structure but also in terms of the regulation of expression, with the exception that the strength of the @entity2829 promoter for the larger transcript is higher. The results strongly suggest that the genetic alterations required to give rise to the C4-type @entity70343 gene were relatively limited.

Characterization of the gene for @entity2388 , @entity6546 dikinase from XXXX , a C3 plant, and a comparison of structure and expression between C3 and C4 genes for this protein.

@entity2829 :: ('4577', 'Species') :: ['maize'] @entity6546 :: ('MESH:D010710', 'Chemical') :: ['orthophosphate'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity70343 :: ('542759(Tax:4577)', 'Gene') :: ['ppdk', 'PPDK'] @entity579 :: ('4530', 'Species') :: ['rice'] @entity2388 :: ('MESH:D019289', 'Chemical') :: ['pyruvate']
@entity579 :: (4530,Species) :: ['rice']
