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The full-length sequence of a putative Triticum aestivum serine/threonine protein kinase gene, named TaSTK, was cloned from a salt-resistant wheat line RH8706-49 based on differential expression studies of this salt-resistant line versus a salt-sensitive line H8706-34 under salt-stress conditions using cDNA-AFLP, RACE and gene amplification methods. The cDNA length is 1958 bp, of which 1431 bp form the open reading frame encoding 476 amino acids. The genomic sequence for the coding region is 4095 bp and includes 5 exons. Bioinformatic analysis suggests that the gene locates in the 2BL and 2DL chromosome and has two copies. The cDNA and genomic sequences have been submitted to GenBank database (Accession No.: AY956328, DQ341377). Expression of the TaSTK mRNA was demonstrated with Northern hybridization to be enhanced under salt conditions, and the degree of salt related enhancement was greater in salt-resistant material RH8706-49 than that in the salt-sensitive material H8706-34. Excess expression of the TaSTK gene, in the form of a TaSTK gene-modified Arabidopsis thaliana material, was demonstrated to increase the growth of the roots in salt containing medium and improve the tolerance of the plant against salt stress.

cDNA-amplified fragment length polymorphism (AFLP) was used to analyze differentially expressed genes in wheat RH8706-49, a salt-stress resistant line (SR) and H8706-34, a salt-stress sensitive line (SS) with or without NaCl stress. A large number of gene fragments related to salt-stress were found. Among them, a full-length cDNA encoding glycogen synthase kinase–shaggy kinase (TaGSK1) was subsequently cloned from SR leaves. The corresponding amino acid sequence was deduced and the primary and secondary structures of the protein predicted, that it has a N-terminus outside transmembrane region with a Serine/Threonine (Ser/Thr) protein kinase catalytic domain. The molecular weight of mature peptide is 43.5 kDa and the isoelectric point is 8.66. Northern blot analysis showed that TaGSK1was induced by NaCl stress, and expressed more strongly in SR than in SS. These results suggest that TaGSK1 is involved in wheat response to salt-stress as a part of the signal transduction component. © 2003 Elsevier Ireland Ltd. All rights reserved.