Novel Halophyte EREBP/AP2-type DNA Binding Protein Improves Salt Tolerance in Transgenic Tobacco
SHEN Yi-Guo , YAN Dong-Qing , ZHANG Wan-Ke, DU Bao-Xin, ZHANG Jin-Song LIU Qiang , CHEN Shou-Yi(1. Institute of Genetics and Developmental Biology , The Chinese Academy of Sciences , Beijing 100101, China;2. College of Life Sciences, Northwest Science-Technology University of Agriculture and Forestry, Shaanxi, Tangling, 712100, China;3, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China)
EREBP/AP2-type proteins are members of a large DNA binding protein (DBF) family found in plants. Some members like APETALA2 and AtDREB/CBF can regulate flower development and response to environmental stresses, respectively. To characterize transcription factors involved in plant responses to salt stress, we constructed cDNA library from salt-treated halophyte (Atriplex hortensis) and isolated a novel gene encoding EREBP/AP2-tvpe protein from this library. This cDNA contained an ORF of 723 bp and a long 3'-Untranslated-Region (UTR) of 655 bp. The deduced amino acid sequence showed one conserved DNA binding domain of EREBP/AP2, thus the corresponding gene was named AhDREBl with a calculated molecular mass of 26.1 kD. AhDREBl under the control of CaMV 35S promoter was then transformed into tobacco and nine independent transgenic lines were obtained and subjected to long term salt stress. The results suggested that overexpression of AhDREBl improved the salt tolerance in transgenic tobacco through functioning as a regulatory molecule in response to salt stress. Analysis of Arabidopsis genome in database resulted in dozens of EREBP/AP2-type homologous proteins, of which seven members showed high similarity to AhDREBl. Secondary structure analysis predicted similar arrangement of a-helix in their DNA binding domains.