A cDNA Encoding a PR-1-like Protein in the Model Legume Medicago truncatula

• Published in: Plant physiology (Bethesda) 1995-01, Vol.107 (1), p.273-274
• Main Authors: Urszula Szybiak-Strozycka, Nicole Lescure, Cullimore, Julie V., Pascal Gamas
• Format: Article
• Language: English
• Subjects: Amino acids; Biological and medical sciences; Complementary DNA; Corn; DNA, Complementary; Fundamental and applied biological sciences. Psychology; Gene expression; Genetics; Inoculation; Legumes; Life Sciences; Medicago sativa - genetics; Medicago truncatula; Messenger RNA; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Parasitism and symbiosis; Plant Gene Register; Plant physiology and development; Plant Proteins - genetics; Plant roots; Plants; Plants genetics; Proteins; Rhizobium meliloti; Sequence Homology, Amino Acid; Symbiosis
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.107.1.273

Medicago truncatula has been adopted as a model legume for the nitrogen-fixing symbiosis with Rhizobium meliloti. To identify new genes induced in the early stages of symbiotic nodulation, a subtractive library was constructed from cDNA prepared from roots of this species after inoculation for 6, 24, and 48 h with a wild-type R. meliloti strain, subtracted (in two cycles) against mRNA isolated from similar material inoculated with a non-nodulating (NodA super(-)) mutant. A number of the resulting cDNA clones were tested by northern analysis using the same two populations of mRNA, and a partial cDNA clone was identified that appeared to show a severalfold increase in expression after inoculation with the nodulating strain. This clone was used to probe a nonsubtracted cDNA library of the "induced" plant material, and 11 independent clones were plaque purified. The nucleotide sequence of the cDNA of one of the longest clones, MtPR-1(1), was determined on both strands. A second cDNA was one base shorter at the 5' end but was otherwise identical with the first cDNA over 250 bases from each end. Taken together these results suggest that there is only a single copy of a sequence closely related to the gene MtPR-1 in the M. truncatula genome and that this gene is expressed in roots inoculated with R. meliloti. Using the BLAST family of sequence alignment programs, we found the nucleotide sequence of MtPR-1(1) to be most strongly homologous to sequences of the pathogenesis-related PR-1 proteins from the dicotyledonous plants tobacco, tomato, and Arabidopsis thaliana.