Characterization of a Novel YnSKn Class of Dehydrin-Like cDNAs from Cold Acclimated Red-Osier Dogwood (Cornus sericea L.) Xylem

Abstract

Summary Red-osier dogwood (Cornus sericea L.) is among the most freeze-tolerant plant species. Four cDNAs were isolated from cold acclimated red-osier dogwood xylem and found to encode novel dehydrin-like proteins. The four deduced amino acid sequences were extremely hydrophilic and contained sequence motifs characteristic of the dehydrin family. ROD (red-osier dehydrin) 44, 48 and 60 sequences each contained the Y, S, and K motifs characteristic of dehydrins. Whereas ROD 25 contained the Y and S motifs but lacked the lysine-rich repeat (K segment). A unique aspect of these sequences was that ROD 25, 44, 48 and 60 included 14, 33, 33 and 35 copies, respectively, of a sequence similar to DEYGNP. This is quite different from other dehydrin-like proteins, which typically contained only one to three Y motifs. The function of these highly repeated sequences is not known. Alignment of the deduced amino acid sequences of ROD 44 and ROD 48 revealed 69% identity. Alignment of overlapping regions of ROD 25 and ROD 60 revealed 89% identity. Transcript expression of Rod genes changed seasonally in red-osier dogwood and was correlated to periods of cold acclimation.