OPTIMIZATION OF RHIZOBIAL NOD GENE-INDUCING ACTIVITY ASSAY IN PEA ROOT EXUDATE

The lacZ transcriptional fusion assay of the activation of rhizobial n od genes has been adapted for the microtitration plates. The assay can be performed reproducibly on a microscale, including induction, lysis , and spectrophotometry. The technique facilitates processing of a lar ge number of samples in physiological studies. Using the microplate me thod, the time course of the release of nod-gene inducers from the roo t of noninoculated, hydroponically cultivated, pea (Pisum sativum L.) plants was monitored till the 16th day after germination. The released activity increased with plant age but a high variability among indivi dual plants and days was observed.