Generation of plants with reduced PKc in tubers. A, RNAi construct used to transform potato plants, containing a PCR-amplified, 650-bp fragment homologous to PKCYT1 (PK-cyt) in a hairpin orientation under the control of the B33 patatin promoter. B, PK activity in tuber extracts from five resultant transgenic lines plus wild type assayed at pH 6.9 (*, significant difference from wild-type levels, n = six tubers from six different plants). C, Western blot of tuber extracts probed with an anti-PKc antibody. D, Quantitative real-time RT-PCR expression analysis of PK transcripts for PKCYT1, PKPα1, and PKPβ2 genes in tubers from the PKc transgenic lines and wild type (normalized to wild-type expression levels). *, Significant difference from wild-type levels (P < 0.05). Data represent the mean and se (n = four independent tuber RNA extractions from different plants).