Analysis of the diurnal expression patterns of the tomato chlorophyll a/b binding protein genes. Influence of light and characterization of the gene family.
Steady-state mRNA levels of the chlorophyll a/b binding (cab) proteins oscillate substantially during a diurnal cycle in tomato leaves. This accumulation pattern is also observed in complete darkness, supporting the hypothesis that the expression of cab genes is at least partially regulated by an endogenous rhythm ("biological clock"). The amplitude of the cab mRNA accumulation is dependent on the duration of illumination and the circadian phase in which light was applied to the tomato plants. These results at the molecular level correlate well with the photoperiodic phenomenon. The characterization of the expression pattern of individual members of the cab gene family was attempted. Distinct primer extension products were detected using specific oligonucleotides homologous to the cab 1, cab 4, cab 5 and cab 8 genes. Based on this analysis the transcription start sites of these genes were determined to be between position -70 and -9 upstream of the ATG codon. During the diurnal cycle the cab 1 and cab 4 genes exhibit the same expression pattern; no transcripts detected at 3 and 6 a.m., maximum mRNA levels were measured at noon and decreasing levels in the afternoon.
Institut für Biochemie der Pflanze, Göttingen, W. Germany.
J W
JW
Kellmann
E
E
Pichersky
B
B
Piechulla
D001483:Base Sequence; D002734:Chlorophyll / Q000235:genetics*; D002940:Circadian Rhythm; D017343:Genes, Plant / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D005810:Multigene Family; D015345:Oligonucleotide Probes; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000235:genetics* / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics
D045342:Light-Harvesting Protein Complexes; D015345:Oligonucleotide Probes; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D002734:Chlorophyll