2 MESSENGER-RNAS ARE ENCODING FOR NADPH-CYTOCHROME P450 REDUCTASES IN HELIANTHUS-TUBEROSUS TUBER TISSUES

Three NADPH-cytochrome P450 reductases were previously purified from wounded Jerusalem artichoke tuber tissues with apparent molecular masses of 80, 82 and 84 kDa. The 84 kDa protein has been further characterized and is shown to be N-glycosylated. Western blot analysis shows that only the 82 and 84 kDa proteins are detectable in the quiescent tuber. The 80 kDa protein appears in wounded tissues, and increases rapidly up to 24 h, along with the 82 and 84 kDa proteins. HTR1 and HTR3, two partial cDNA clones coding for Jerusalem artichoke NADPH-cytochrome P450 reductases which display 84% amino acid positional identity, were used to perform Northern blot analysis of RNA from quiescent and wounded tuber tissues. HTR1 hybridizes more strongly with a 2.4 kb mRNA and HTR3 with a 2.6 kb mRNA. Hybridization of both probes was strongly enhanced in response to wounding. These results indicate that at least two messenger RNAs are encoding for the reductases in Helianthus tuberosus tuber.