PARENT SESSION
Poster Session 12: Physiology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Interaction between cyclin-dependent kinases and nitrate reductase activity in Phaseolus vulgaris roots grown under nitrogen deficit.
Hansberry, Janis*,1, Neuman, Dawn1, 1 University of Nevada, Las Vegas, Las Vegas, NV, U.S.A.
ABSTRACT- In well-aerated soils, nitrate (NO3-) is the major nitrogen source available for uptake by vascular plants. (NO3-) initially is reduced to nitrite ((NO2-) through the activity the cytosolic enzyme NAD(P)H-nitrate reductase (NR; EC 1.6.6.1-3). Excess (NO3-)may potentially contribute to ground and surface water pollution through leaching and soil erosion. Conversely, additional (NO3-) taken up by plants accumulates in tissues; it has been implicated in the occurrence of methaemoglobinemia (Blue Baby Syndrome) and possibly other diseases, such as gastric cancers. Its accumulation in plants is of major concern to all involved and remains a significant limitation to agriculture. Because of its importance in the production of new growth, understanding the role of NR in vascular plants is of potential economic importance, especially in light of recent studies illuminating the enzyme as one focal point for the controlled integration of carbon and nitrogen metabolism. There is also increasing evidence of the participation of phytohormonal modification in controlling the integration of responses to nitrogen deficit. Cytokinins (CK's) are principle regulators of cell cycle progression through checkpoint activation and, as such, exhibit gradations in activity levels. Recent collaborations with the Czech Republic have brought together two labs working on identification of three cyclin-dependent kinases (CDK's) proposed to be novel cytokinins; Bohemine, Roscovitine, and Olomoucine. Their importance is concomitantly being investigated due to their antagonistic effect on tumor suppressor cells and oncogenes. The purpose of this study is to contribute to the developing body of knowledge in the field of phytohormonal ecology. We are currently analyzing the effects of these compounds on NR activity in the roots of Phaseolus vulgaris grown under nitrogen deficit for determination whether these compounds can be labeled as cytokinins or cytokinin inhibitors.
Key words: Nitrate Reductase, Cytokinins, CDK's, Nitrogen Deficit