Organisation and expression of a potato (Solanum tuberosum) protein kinase gene

A 4.3 kb genomic clone from potato (Solanum tuberosum) cv. Saturna has been isolated which contains the full coding sequence of a protein kinase gene (Stpk1), 1 kb of 3' sequence, and the first exon of a neighbouring gene encoding a sucrolytic enzyme. An identical organisation could be detected in a genomic clone carrying a gene that encodes a protein kinase homologue in Arabidopsis thaliana (Hayashida et al., Gene, 121 (1992) 325-330). Southern and RT-PCR analyses indicate that Stpk1 is a single copy gene which is expressed throughout the plant with an increase in transcript abundance in leaf after infection with Phytophthora infestans. While comparisons using the deduced amino acid sequence for STPK1 indicate that it is most closely related to cyclic nucleotide-dependent protein kinases, it contains an additional plant-specific insert of 85 amino acids in the catalytic domain.