Abscisic Acid Stimulation of Nitrate Reductase Activity in Potato Tuber Slices : Effect of Inhibitors of Protein and Nucleic Acid Synthesis

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概要

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• Pretreatment of potato tuber slices with ABA for 22 hr, in the absence of exogenous NO_3 resulted in stimulation of nitrate reductase activity (NRA) and increase in endogenous NO_3 content. The increased tissue NO_3 level suggests the conversion of organic nitrogen to NO_3. Upon transferring slices to 25 m_M KNO_3 there was a marked stimulation of NRA and NO_3 accumulation. Addition of cycloheximide (CHM) at the start of ABA pretreatment abolished the NRA response but stimulated NO_3 accumulation. Actinomycin D (ACTD) pretreatment stimulated NRA and maintained a high level of activity throughout the incubation period. In combination with ABA ACTD suppressed the ABA response during the first 10 hr of incubation after which there was a slight increase. With fresh unpretreated slices CHM alone and in combination with ABA suppressed NRA throughout the incubation period while ACTD slightly reduced activity during the first 10 hr before stimulating it. Combined pretreatment with ABA and ACTD elicited the greatest stimulation of NRA. Abscisic acid stimulated NRA only after 24 hr but significantly enhanced tissue NO_3 accumulation which was suppressed by CHM alone and in combination with ABA but not affected by the other treatments. These results suggest that the ABA response requires protein synthesis but may be independent of RNA transcription. These findings support the view that mRNA for nitrate reductase translation is stable in some tissues. Both ABA and ACTD probably enhanced NRA by suppressing the production of inhibitory substances thereby reducing normal fluctuations in enzyme activity.

著者

• Palmer C.e.

  Department Of Botany And Biology Teaching Unit University Of Manitoba

関連論文

• Abscisic Acid Stimulation of Nitrate Reductase Activity in Potato Tuber Slices : Effect of Inhibitors of Protein and Nucleic Acid Synthesis
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• Inhibition of nitrate accumulation and in vivo nitrate reductase activity in potato tuber slices by dimethysulfoxide
• Influence of Abscisic Acid on Nitrate Accumulation and Nitrate Reductase Activity in Potato Tuber Slices

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