Abstract:

To understand the gene expression characteristics, which involved in drought tolerance, five cDNA libraries were constructed using suppression subtractive hybridization (SSH) method with wheat seedlings sampled at 1, 6, 12, 24 and 48 hours of water stress, respectively. By sequencing, 6 733 ESTs were obtained from the cDNA libraries. The gene expression profile induced by water stress in wheat seedling has been preliminarily constructed after assembling, homologous comparing, annotating and classifying the EST sequences. The dynamic characters and 4 patterns of gene expression during water stress treatment were found. The expression pattern 1 in which the most genes were detected at the initial stage, but the number of genes decreased to the least at 12th hour of water stress, then gradually increased with water stress undergone continuously, included genes involved in repair and protection from damage. The pattern 2 with the fewer genes at the initial stage, but the gene number increased-decreased-increased gradually with the water stress process of time, which was protein synthesis-related genes. The pattern 3 was that gene number was fewer at the initial stage, but gradually increased to the most at 12^th hour, then gradually decreased, such as protein kinase gene. Number of genes in the pattern 4 was higher at the initial stage, and then decreased-increased-decreased gradually along with the water stress elongation, to which protein phosphatase gene belongs. Among 648 uni-genes of known function annotation, the proportion of transcription factor genes was 6.17%, protein phosphatase genes 2.16%, protein kinase genes 4.01%, genes involved in repair and protection from damage 19.90%, genes of macromolecule protection factor 2.0%, membrane protein genes 9.11%, which may be important gene classifications related to drought resistance. The result was helpful to completely comprehend genetic mechanism of drought resistance in wheat, to discover and utilize key genes in the improvement of crop drought resistance.

Key words: Wheat, SSH, Water stress, Gene expression profile