作者： Peterj . Davies , Alanm . Kinnersley
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摘要: Anthocyanin synthesis, hairformation, andthesynthesis ofascorbic acidoxidase areanphytochrome-medisted reactions occurring inthe hypocotyl ofmustard (Sinapis albaL.),controlled byphytochrome actully located inthehypocotyl. A comparison ofthese three showed thatincertain respects theydiffer greatly intheir response to light. Theability oftheseedling torespond tolight byshowing thethree responses wasstrongly influenced bythestate ofdevelopment ofthe seedling. Whitelight given veryearly after seedimbibition wasunable evokeanyofthethreereactions. By 50hoursafter imbibition, all systems werefully inducible bylight. Theaddition ofactinomycin D toa fully competent seedling coincident withillumination strongly inhibited thedevelopment ofallthreeresponses. Incontrast, theaddition of cordycepin atthis timeinhibited thesynthesis ofanthocyanin andascorbicacidoxidase buthadnoeffect onhairformation. Cycdoheximide whengiven uptoseveral hoursafter Thissuggests thenecessity forRNA andprotein synthesis forlightinduced expression reactions, andthattheRNA species involved inthethree mayhavediffering degrees ofpolyadenylation. Thelagperiod between theonset oflight andthefirst display was3hoursforanthocyanin andascorbic andabout5hours forhair formation. Amountsoflght sufficient givelarge increases inthelevels andhair formation gaveamuchsmaUler increase inanthocyania synthesis. Hair acid oxidase showedamuchgreater sensitivity toinduction atearly stages ofseedling development thandid anthocyanin Following aninductive light period, wassensitive tofarredlight inhibition foraperiod twice aslong astheother tworeactions. Thedifferences intheresponse ofthethree sggest that thephytochrome-mediated which control their also differ.