Isolation and characterization of two different cDNAs of delta1-pyrroline-5-carboxylate synthase in alfalfa, transcriptionally induced upon salt stress

• Published in: Plant molecular biology 1998-11, Vol.38 (5), p.755-764
• Main Authors: Ginzberg, I, Stein, H, Kapulnik, Y, Szabados, L, Strizhov, N, Schell, J, Koncz, C, Zilberstein, A
• Format: Article
• Language: English
• Subjects: 1-Pyrroline-5-Carboxylate Dehydrogenase; Amino Acid Sequence; Base Sequence; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Medicago sativa - chemistry; Medicago sativa - enzymology; Medicago sativa - genetics; Molecular Sequence Data; Oxidoreductases Acting on CH-NH Group Donors - genetics; Plant Roots - chemistry; Plant Roots - drug effects; Plant Roots - metabolism; Proline - drug effects; Proline - metabolism; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; Sodium Chloride - pharmacology; Space life sciences; Transcription, Genetic - drug effects
• ISSN: 0167-4412

Two different cDNA clones, MsP5CS-1 and MsP5CS-2, encoding delta1 -pyrroline-5-carboxylate synthase (P5CS). the first enzyme of the proline biosynthetic pathway, were isolated from a lambdaZap-cDNA library constructed from salt stressed Medicago sativa roots. MsP5CS-1 (2.6 kb) has an open reading frame of 717 amino acids, as well as a non-spliced intron at a position corresponding to the evolutionary fusion point of the bacterial proA and proB genes. MsP5CS-2 (1.25 kb) is a partial clone. The clones share 65% identity in nucleotide sequences, 74% homology in deduced amino acid sequences, and both show a high similarity to Vigna aconitifolia and Arabidopsis thaliana P5CS cDNA clones. Southern blot analysis confirmed the presence of two different P5CS genes. The effect of salinity on the transcription of MsP5CS-1 and MsP5CS-2 in roots was studied, using northern blot analysis and a RT-PCR approach. A rapid increase in the steady-state transcript level of both genes in roots was observed by RT-PCR upon exposure of hydroponically grown 6-day old seedlings to 90 mM NaCl, suggesting that both are salt-inducible genes, yet a higher response was observed for MsP5CS-2.