Nitrate reductase and the biological clock

Different transgenic and mutated plants altered in the nitrate reductase (Nia) genes or central clock genes will be investigated. The data will be evaluated with the help of kinetic/mathematical models to test for the possible influence of a centra l clock on NR expression as opposed to Nia/NR constituting a self-sustained feedback oscillator. NR mutated at the regulatory phosphorylation site (serine 521) will be characterized. The physiology of these transgenic plants (niaser will be studied and is expected to shed light on the importance of phosphorylation in relation to environmental factors. Effects of phosphorylation on stability and degradation of NR will be examined and possible implications for the period length of NR rhythms