Plant basic-leucine zipper （bZlP） transcription factors play important roles in many biological processes. In the present study, a bZlP gene, GmbZIP132, was cloned from soybean and its biological function under abiotic stresses was studied. The transcription of GmbZIP132 was induced by drought and high salt treatments. Among all of the organs analyzed, its expression was the highest in cotyUedon and stems. GmbZIP132 could weakly bind to the GCN4-1ike motif （GLM） （5＇-GTGAGTCAT-3＇） in yeast one-hybrid assay. Compared with wild-type （WT） Arabidopsis plants, transgenic plants overexpressing GmbZlP132 showed reduced abscisic acid sensitivity and increased water loss rate. At the stage of germination, transgenic plants were more tolerant to salt treatment than wild-type plants. The expression of some abiotic stress-related genes, such as rd29B, DREB2A, and PSCS, were upregulated in the transgenic plants. These results indicated that GmbZlP132 was an abioUc stress-related gene, and its overexpression could increase the salt tolerance of transgenic Arabidopsis plants during germination, yet no significant difference of tolerance to abiotic stresses was found between transgenic and wild type plants at the seedling stage.
Plant seed development and germination are under strict temporal and spatial regulation, and tran-scription factors play important roles in this regulation. In the present study we identified an EST ex-pressed specifically in the developing soybean seeds. The full length of the gene was obtained through further RACE analysis and the gene was named GmSGR. Sequence analysis revealed that this gene belonged to the AP2/ERF transcription factor family. Its AP2 domain had the highest similarity with that of the A-3 member AtABI4 of DREB subgroup in the AP2/ERF family in Arabidopsis. GmSGR did not exhibit transcriptional activation activity in the yeast assay system. GmSGR was overexpressed in Arabidopsis and the germination rates of the transgenic seeds were significantly higher than that of the wild type seeds under higher concentrations of ABA and glucose respectively. However, the germina-tion rates of the transgenic seeds were lower than that of control under salt stress. The expression of AtEm6 and AtRD29B was higher in the seedlings of the transgenic plants than that in the wild-type seedlings. These results suggest that GmSGR may confer reduced ABA sensitivity and enhanced salt sensitivity to the transgenic seeds through regulating the expression of AtEm6 and AtRD29B genes.
WANG ChunMei, WANG HuiWen, ZHANG JinSong & CHEN ShouYi National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Bei-jing 100101, China
