Processing of vertebrate box C/D small nucleolar RNAs in plant cells

The recent isolation of a number of plant box C/D small nucleolar (sno)RNAs demonstrates the conservation in plants of sequence and structural elements of processed box C/D snoRNAs. Boxes C and D, and terminal inverted repeats are known to be essential for accumulation and processing in vertebrates and yeast. Processing of vertebrate box C/D snoRNAs was examined by expression of various mouse hsc70 intron 5‐U14 constructs in tobacco protoplasts. Full‐length U14 and internally deleted U14 accumulated in the plant cells. Human U3 and U8 fragments, consistent with processing to internal box C/C′ sequences, also accumulated in the plant cells. The similarity of processing behaviour of the vertebrate box C/D constructs in tobacco protoplasts and Xenopus oocytes suggests the mechanism of processing, involving recognition and association of proteins, is conserved in plants.