Isolation and characterization of two Medicago falcate AP2/EREBP family transcription factor cDNA, MfDREB1 and MfDREB1s.

DREB transcription factors play an important role in tolerance to abiotic stress in high plants. In this work, two new DRE-binding protein genes MfDREB1 and MfDREB1s cDNA that encoded an AP2/EREBP type transcription factor were isolated by RT-PCR from Medicago falcate seedlings. Sequence analysis showed MfDREB1 and MfDREB1s were almost identical except that there was a 202bp fragment at the 3' end of the MfDREB1s cDNA that is absent in MfDREB1 cDNA. The MfDREB1 has a open reading frame of 651bp, which encodes 216 amino acid residues. The putative protein is deduced a predicted molecular mass of 24.6kDa and a pI of 5.95. The MfDREB1s has a open reading frame of 555bp, the putative protein is 184 amino acid long with a predicted molecular weight of 20.8kDa, pI 9.11. The Protein Blast data revealed that the two proteins can be classified as a typical member of the AP2/EREBP family of DNA-binding proteins. The comparison of the MfDREB1 cDNA and MfDREB1s cDNA with their corresponding genes in genomic DNA showed that the size and nucleotide sequence of the cDNA was identical to that of the genomic DNA. This suggested that the genomic MfDREB1 gene and MfDREB1s gene had no introns. Southern blot analysis indicated that MfDREB1 and MfDREB1s are multi-copy genes in Medicago falcate genome. Northern blot analysis indicated that the MfDREB1 and MfDREB1s genes were induced by low temperature stress.
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