A DEHYDRIN COGNATE PROTEIN FROM PEA (PISUM-SATIVUM L) WITH AN ATYPICAL PATTERN OF EXPRESSION

Dehydrins are a family of proteins characterised by conserved amino ac id motifs, and induced in plants by dehydration or treatment with ABA. An antiserum was raised against a synthetic oligopeptide based on the most highly conserved dehydrin amino acid motif, the lysine-rich bloc k (core sequence KIKEKLPG). This antiserum detected a novel M(r) 40000 polypeptide and enabled isolation of a corresponding cDNA clone, pPsB 61 (B61). The deduced amino acid sequence contained two lysine-rich bl ocks, however the remainder of the sequence differed markedly from oth er pea dehydrins. Surprisingly, the sequence contained a stretch of se rine residues, a characteristic common to dehydrins from many plant sp ecies but which is missing in pea dehydrin. The expression patterns of B61 mRNA and polypeptide were distinctively different from those of t he pea dehydrins during seed development, germination and in young see dlings exposed to dehydration stress or treated with ABA. In particula r, dehydration stress led to slightly reduced levels of B61 RNA, and A BA application to young seedlings had no marked effect on its abundanc e. The M(r) 40 000 polypeptide is thus related to pea dehydrin by the presence of the most highly conserved amino acid sequence motifs, but lacks the characteristic expression pattern of dehydrin. By analogy wi th heat shock cognate proteins we refer to this protein as a dehydrin cognate.