Isolation and characterization of a dehydrin gene from white spruce induced upon wounding, drought and cold stresses

A cDNA clone encoding a dehydrin gene was isolated from a cDNA library prep ared from white spruce (Picea glauca) needle mRNAs. The cDNA, designated Pg Dhn1, is 1159 nucleotides long and has an open reading frame of 735 bp with a deduced amino acid sequence of 245 residues. The PgDhn1 amino acid seque nce is highly hydrophilic and possesses four conserved repeats of the chara cterized lysine-rich K-segment (EKKGIMDKIKEKLPG), and an 8-serine residue s tretch prior to the first lysine-rich repeat that is common to many dehydri ns. The DEYGNP conserved motif is, however, absent in the PgDhn1 sequence. In unstressed plants, the highest level of transcripts was detected in stem tissue and not fully expanded vegetative buds. PgDhn1 expression was also clearly detected in reproductive buds, at various stages of development. Th e mRNAs corresponding to PgDhn1 cDNA were induced upon wounding and by jasm onic acid (JA) and methyl jasmonate (MeJa) treatments. Upon drought stress, increased transcript accumulation was observed in needle tissue reaching a maximum level 48 h after treatment. Treatments of seedlings with abscisic acid or ethephon also resulted in high levels of transcript accumulation in needle tissue. Finally, cold induction of PgDhn1 transcripts was also dete cted as early as 8 h after treatment.