A survey of transcripts expressed specifically in root nodules of broadbean (Vicia faba L.).
More than 600 potentially nodule-specific clones have been detected by differential hybridization of a broadbean cDNA library constructed from root nodule poly(A)+ RNA. These isolated cDNAs belong to at least 28 different clone groups containing cross-hybridizing sequences. The number of clones within a clone group varies from about 200 to only one single clone. Northern hybridization experiments revealed nodule-specific transcripts for 14 clone groups and markedly nodule-enhanced transcripts for another 7 clone groups. Sequence homologies indicate that three transcript sequences code for different leghemoglobins. Two other transcripts encode a nodule-specific sucrose synthase and a nodule-enhanced asparagine synthetase, respectively. Four deduced gene products are proline-rich, two of them being the homologues of PsENOD2 and PsENOD12. The third proline-rich protein (PRP) is composed of similar amino acid repeats as the nodule-specific PsENOD12 but is expressed in nodules and roots in comparable amounts. The fourth PRP is a nodule-enhanced extensin-type protein built up by Ser-Pro4 repeats. Two further nodule-specific transcripts encode gene products showing some similarity to structural glycine-rich proteins. Additionally, transcripts could be identified for broadbean homologues of the nodulins MsNOD25, PsENOD3 and PsENOD5 and transcripts specifying a nodule-enhanced lipoxygenase and a translation elongation factor EF-1 alpha, which is expressed in all broadbean tissues tested.
Lehrstuhl für Genetik, Fakultät für Biologie, Universität Bielefeld, Germany.
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AM
Perlick
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Pühler
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary; D007887:Fabaceae / Q000033:anatomy & histology / Q000235:genetics*; D015723:Gene Library; D008084:Lipoxygenase / Q000235:genetics; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000235:genetics; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000235:genetics; D010455:Peptides / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D010946:Plants, Medicinal; D055232:Proline-Rich Protein Domains; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D010455:Peptides; D010940:Plant Proteins; D012333:RNA, Messenger; D008084:Lipoxygenase