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

Three NADPH-cytochrome P450 reductases were previously purified from w ounded Jerusalem artichoke tuber tissues with apparent molecular masse s of 80, 82 and 84 kDa. The 84 kDa protein has been further characteri zed and is shown to be N-glycosylated. Western blot analysis shows tha t only the 82 and 84 kDa proteins are detectable in the quiescent tube r. The 80 kDa protein appears in wounded tissues, and increases rapidl y up to 24 h, along with the 82 and 84 kDa proteins. HTR1 and HTR3, tw o 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 woun ded tuber tissues. HTR1 hybridizes more strongly with a 2.4 kb mRNA an d HTR3 with a 2.6 kb mRNA. Hybridization of both probes was strongly e nhanced in response to wounding. These results indicate that at least two messenger RNAs are encoding for the reductases in Helianthus tuber osus tuber.