关键词: 小麦, 水分胁迫, 低温, 基因克隆

Abstract: Abstract: Water stress and cold is important factors to restrict plant growth. However, there is little knowledge on the function of stress-responsive genes in plant. Therefore it is necessary to clone some important novel genes to study the mechanism of plant adaptation to water stress and to improve plant resistance against drought. A water stress-induced gene (designated as W89) was cloned from the cDNA library of drought-treated wheat seedings by phage hybridization in situ. The full-length cDNA of W89 consists of 1059 bp and contains a 696 bp open reading frame (ORF) encoding a 232-amino-acid protein (fig.1). Southern blot analysis indicated that W89 was a single-copy gene (fig.3). RT-PCR analysis revealed that the expression of W89 was upregulated by abscisic acid (ABA), drought and cold (fig.4). The highest expression levels of W89 were induced by ABA and cold for more than 5 hrs, and by drought treatment for more than 2 hrs. Amino acid sequence analysis discovered that W89 had a conserved region of DUF248, which contained a methyltrasferase domain with a SAM-binding motif (fig.1). Phylogenetic analysis showed that W89 was 66% identical to Oryza sativa dehydration-responsive protein (BAD67956) (fig.2). It was supposed that W89 was a novel dehydration-responsive protein encoding gene. Based on the functions of methyltrasferase and SAM-binding motif, the SAM-binding motif of W89 was supposed to be connected with other proteins or transcription factors to transduct stress signals and finally regulate the expression of stress-responsive genes on the early time of drought stress.