Abstract
Changes in the activities of three enzymes (nitrate reductase, l-phenylalanine ammonia-lyase, and a dehydronicotinamide adenine dinucleotide-oxidase complex) were measured during development of water stress in young maize (Zea mays) plants.
l-Phenylalanine ammonia-lyase and nitrate reductase activities decreased markedly with water deficits of 10 to 20%. The activities did not reach zero at water deficits as high as 50%, but appeared to approach a new steady state. Partial to complete recovery of enzyme activity occurred 24 hours after rehydration of the stressed plants. The oxidase activity did not respond to water stress in the same manner as that of the other two enzymes.
It is suggested that the level of enzyme activity is a consequence of an equilibrium between the rates of synthesis and degradation, and that progressive tissue dehydration reduces both the enzyme synthesis and the enzyme-inactivating systems.
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Selected References
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- Beevers L., Schrader L. E., Flesher D., Hageman R. H. The Role of Light and Nitrate in the Induction of Nitrate Reductase in Radish Cotyledons and Maize Seedlings. Plant Physiol. 1965 Jul;40(4):691–698. doi: 10.1104/pp.40.4.691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Filner P., Varner J. E., Wray J. L. Environmental or developmental changes cause many enzyme activities of higher plants to rise or fall. Science. 1969 Jul 25;165(3891):358–367. doi: 10.1126/science.165.3891.358. [DOI] [PubMed] [Google Scholar]
- Hageman R. H., Flesher D. Nitrate Reductase Activity in Corn Seedlings as Affected by Light and Nitrate Content of Nutrient Media. Plant Physiol. 1960 Sep;35(5):700–708. doi: 10.1104/pp.35.5.700. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ingle J. The regulation of activity of the enzymes involved in the assimilation of nitrate by higher plants. Biochem J. 1966 Sep;100(3):577–588. doi: 10.1042/bj1000577. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schrader L. E., Ritenour G. L., Eilrich G. L., Hageman R. H. Some characteristics of nitrate reductase from higher plants. Plant Physiol. 1968 Jun;43(6):930–940. doi: 10.1104/pp.43.6.930. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Travis R. L., Jordan W. R., Huffaker R. C. Evidence for an Inactivating System of Nitrate Reductase in Hordeum vulgare L. during Darkness That Requires Protein Synthesis. Plant Physiol. 1969 Aug;44(8):1150–1156. doi: 10.1104/pp.44.8.1150. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zucker M. Induction of phenylalanine ammonia-lyase in Xanthium leaf disks. Photosynthetic requirement and effect of daylength. Plant Physiol. 1969 Jun;44(6):912–922. doi: 10.1104/pp.44.6.912. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zucker M. Rate of phenylalanine ammonia-lyase synthesis in darkness. Biochim Biophys Acta. 1970 May 12;208(2):331–333. doi: 10.1016/0304-4165(70)90253-9. [DOI] [PubMed] [Google Scholar]
- Zucker M. Sequential Induction of Phenylalanine Ammonia-lyase and a Lyase-inactivating System in Potato Tuber Disks. Plant Physiol. 1968 Mar;43(3):365–374. doi: 10.1104/pp.43.3.365. [DOI] [PMC free article] [PubMed] [Google Scholar]
