烟草愈伤组织多酚氧化酶研究

柳叶烟草愈伤组织中多酚氧化酶氧化邻苯二酚的活性明显高于氧化对苯二酚的活性。当以邻苯二酚为底物时,烟草愈伤组织多酚氧化酶分别在pH 5.6和pH 7.4有两个活性高峰。KCN、Dieca和m-CLAM对烟草愈伤组织多酚氧化酶活性都有明显抑制效应。根据凝胶电泳分析,继代培养愈伤组织多酚氧化酶同工酶有5条酶带,而巳分化出芽原基的愈伤组织和新分化长出的小叶都有7—8条酶带。继代培养的愈伤组织多酚氧化酶主要存在于除去线粒体的上清液中,线粒体部分也可测出酶活性。继代培养愈伤组织在接种后18天内,多酚氧化酶活性无重大改变。在此期间,Dieca对呼吸的抑制效应也变化不大。分化组织多酚氧化酶活性显著高于继代培养愈伤组织,在芽原基形成后,酶活性明显升高;此时Dieca对呼吸的抑制也由32%上升到47%。

STUDIES ON POLYPHENOL OXIDASE IN TOBACCO CALLU CULTURES

Many studies have been made on poly-phenol oxidase in plant tissues.However,there are only a few reports on the polyphenol oxidase in plant callus.In this paper,the callus cultures of Nicotiana tobacum cv.Wil-low leaf were used as experimental materials in order to clear some properties and changes of polyphenol oxidase during callus differen-tiation and organ formation. The polyphenol oxidase of tobacco callus can oxidize catechol and hydroquinone,but the activity oxidizing hydroquinone was ra-ther low.Two activity peaks of the enzyme were observed around PH5.6 and PH7.4 with catechol as substrate.The polyphenol oxidase activity was obviously inhibited by KCN,Dieca and m-CLAM.According to the gel electrophoresis analysis,the isoenzymes of polyphenol oxidase in subcultured callus ex-pressed five bands,but in the callus differen-tiating into bud and the small leaves regene-rated from callus seven to eight bands were observed.During the 18 days of culture,the polyphenol oxidase activity of subcultured callus did not change obviously.The polyphe-nol oxidase activity of differentiating callus was much higher than that of subcultured callus.A significant increase in polyphenol oxidase was observed during bud formation,at the same time the inhibition of Dieca on respiration also increased from 32% to 47%.