Isolation and characterization of cDNA clones for NADP-malic enzyme from leaves of Flaveria: transcript abundance distinguishes C3, C3-C4 and C4 photosynthetic types.
To study the control of enhanced synthesis of enzymes associated with C4 photosynthesis relative to non-C4 plants, we investigated the expression of NADP-malic enzyme (NADP-ME) in different photosynthetic types of Flaveria. Complementary DNA clones encoding NADP-ME were constructed using poly(A)+ RNA from leaves of Flaveria trinervia (C4) and F. linearis (C3-C4) and identified by homology to a cDNA clone (500 bp) encoding NADP-ME from maize (Zea mays L. [39]). The sequence of one clone from each species was determined. The Flaveria clones were 90% homologous over a 564 nucleotide region encoding the carboxy terminal end of the derived polypeptide; sequence similarity to the maize transcript in this region was 71%. Both Flaveria clones detected a 2/3 kb transcript by hybridization to poly(A)+ RNA from expanding leaves of F. trinervia, F. linearis and F. pringlei (C3). The level of transcripts paralleled previously observed NADP-ME activity and abundance differences determined in these species, suggesting that control of the expression of NADP-ME in different photosynthetic types is predominantly at the transcriptional/post-transcriptional level. Southern analysis of genomic DNAs from F. trinervia, F. linearis and F. pringlei indicated a low copy number for this gene in all three species.
Rajeevan
M S
MS
Department of Agronomy, University of Georgia, Athens 30602.
Bassett
C L
CL
Hughes
D W
DW
D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA; D008291:Malate Dehydrogenase / Q000235:genetics*; D008969:Molecular Sequence Data; D010788:Photosynthesis; D010944:Plants / Q000201:enzymology / Q000235:genetics
D004247:DNA; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)