Gene Expression Profiles of Response to Water Stress at the Jointing Stage in Wheat

Drought is one of the most adverse environmental factors that impact on plant growth and reduce crop yields. To decipher the molecular mechanism of drought tolerance, we constructed a cDNA library using suppression subtractive hybridization (SSH) and dissected the gene expression profiles in seedling and jointing wheat plants after stress with PEG-6000. A total of 2 046 ESTs from the jointing stage library (J-Lib) were allocated to 961 contigs. Among the ESTs, 265 uni-genes in 12 categories were identified on the basis of sequence similarities and functional classifications. Most were known to be involved in protection, directly or indirectly, against water stress. To determine differences in gene expression profiles for water stress responses at the jointing and seedling stages, data from the J-Lib were compared with those from a 2-leaf seedling library (S-Lib) constructed by the same method. Significant differences were observed between the two libraries for function-known genes; signal transduction genes were far more active at jointing than at the seedling stage.