The temporal and spatial transcription pattern in root nodules of Vicia faba nodulin genes encoding glycine-rich proteins.
Four different transcript sequences encoding gene products with an unusually high glycine content were identified in Vicia faba root nodules. Northern blot analysis revealed a strong nodule specific expression of the corresponding genes. Time course experiments showed that two of these genes were transcribed before the onset of leghemoglobin expression and hence were designated VfENOD-GRP2 and VfENOD-GRP5, whereas the first detection of VfNOD-GRP1 and VfNOD-GRP4 transcripts coincided with the appearance of leghemoglobin transcripts in V. faba root nodules. A characteristic feature of all encoded nodulins was a hydrophobic N-terminus, which in the case of the nodulins ENOD-GRP2 and ENOD-GRP5 has the characteristics of a signal peptide. Such a structure is comparable to other plant glycine-rich proteins decribed as components of the plant cell wall. Based on tissue print hybridizations, we found that VfNOD-GRP1, VfENOD-GRP2 and VfNOD-GRP4 were expressed in the interzone II-III and in the whole nitrogen-fixing zone III. In contrast to VfENOD-GRP2 and VfNOD-GRP4, the signal intensity of hybridizing VfNOD-GRP1 transcripts was slightly reduced in the more proximal part of broad bean root nodules. Apart from the interzone II-III and the nitrogen fixing zone III, VfENOD-GRP5 RNA was also detected in large areas of the prefixing zone II.
Schroder
G
G
Universitat Bielefeld, Lehrstuhl fur Genetik, Germany.
Fruhling
M
M
Puhler
A
A
Perlick
A M
AM
D000595:Amino Acid Sequence; D007887:Fabaceae / Q000235:genetics* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D005998:Glycine; D007874:Leghemoglobin / Q000096:biosynthesis; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D018517:Plant Roots; D010946:Plants, Medicinal; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014158:Transcription, Genetic
D007874:Leghemoglobin; D008565:Membrane Proteins; D010940:Plant Proteins; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; C045625:nodulin; D005998:Glycine