Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract only
Publication Acceptance Date: 7/1/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Many agriculturally important legumes assimilate most of the ammonium produced by nitrogen fixation into the ureides allantoine and allantoic acid. In bean plants, ureides synthesis is closely related to symbiotic N2-fixation capacity. On the basis of the involvement of ureides in a symbiotic relationship, a study was undertaken to obtain an indication of the bacterial signals possibly implicated in purine catabolism by examinin patterns of enzymatic activities in bean nodules inoculated with Rhizobium strains mutated in the electron transport chain. Nodules containing the wild type Rhizobium strain CE3 had higher amounts of ureides than nodules induced with the mutant CFN037, which was selected for its higher respiratory capability. In contrast, CFN037 infected nodules had a higher aspartate aminotransferase (AAT) activity. These results suggest that an increase in bacterial respiration promotes a reduction in ureide synthesis and an increase in the transport of amides. There were no differences observed in uricase, glutamine synthetase, and phosphoenolpyruvate carboxylase (PEPc) activities between these two nodule types. In contrast, glutamate synthase (GOGAT) activity in CFN037 nodules was two to three times higher than in CE3 nodules. Two PEPc (PvPEPc-2 and PvPEPc-5) and two GOGAT (PvGOGAT-4 and PvGOGAT-15) cDNAs have been found in bean. Its differential expression in nodules is currently being studied and will be presented and discussed in relation to the aforementioned results.