Functional Analysis On LeDREB1 Transcription Factor Gene Of Tomato In Transgenic Arabidopsis

The LeDREB1 gene (GenBank accession No.: AF500011) was isolated from a tomato cDNA Library by yeast mono-hybrid screening,and had one open reading frame of 900bp length. The LeDREB1 gene contains an AP2/EREBP conserved region composed of 58 amino acids, and had a nuclear location signal region and a transcriptional activation region on N-terminate and C-terminate respectively.Based on the previous research, two vectors, pCAMBIA1304 and pCAMBIA 2300-OCS with LeDREB1 were successfully constructed, respectively. Expression vector was transferred into wild type Arabidopsis with the method of floral-dip. Nine positive seedlings of T0 generation were selected by Hygromycine, PCR, and GUS detection. The screening results of resistant separation ration of T1 transgenic seeds was close to 3:1. The results indicated that exogenous gene LeDREB1 could be inserted by single-copy in chromosome of transgenic lines. Two homozygous transgenic lines were obtained.The GUS gene was over expressed in main roots, lateral roots and hypocotyls, whereas, they were little expressed in cotyledons.For further investigated the function of LeDREB1, wild type and transgenic plants were treated by drought and high-salt stresses. The physiological analysis demonstrated that the transgenic plants grew significantly better than wild type after drought and high-salt stresses, and water contents of transgenic plants increased much more than that of wild type. MDA contents of both transgenic and wild type plants increased under the drought and high-salt stresses, but MDA contents in wild type plants increased much more than that in the transgenic plants. Contents of soluble sugars and proline in transgenic lines were significantly higher than in wild type. These results indicated that the tolerance of transgenic lines was remarkably better than wild type attributed by the insertion of target-gene LeDREB1.RT-PCR analysis of transgenic plants indicated that the expression of genes kin1 and cor6.6 increased along with period of salt and low temperature stresses. The expression peak of genes kin1 and cor6.6 was achieved after 1h salt treatment. The expression peak of genes kin1 and cor6.6 was achieved after 3h temperature stress and the expression maintained great amount. Transcription factor LeDREB1 can regulate the expression of downstream genes under high-salt and low-temperature conditions.