Nitrate Induced Nodule Senescence and Changes in Activities of Enzymes Scavenging H2O2 in Clusterbean (Cyamopsis tetragonaloba Taub.)

Involvement of Activated Oxygen in Nitrate-Induced Senescence of Pea Root Nodules

“…The inhibitory effect of nitrate ranged from approximately 16% for catalase and MDHA reductase to 45% for ASC peroxidase and GSH (Tables I11 and IV). Comparison of our results with e a r l i e r reports on the antioxidant capacity of nitrate-treated nodules (Becana et al, 1988;Swaraj et al, 1993; With these reservations in mind, some analogies can be drawn from the different studies. For example, catalase activity was inhibited by 20 to 30% after treatment of alfalfa nodules with 20 mM nitrate for 7 d (Becana et al, 1988), clusterbean nodules with 50 mM nitrate for 3 d (Swaraj et al, 1993), or lupin nodules with 20 mM nitrate for 4 to 6 d (Lorenzo et al, 1994).…”

“…Comparison of our results with e a r l i e r reports on the antioxidant capacity of nitrate-treated nodules (Becana et al, 1988;Swaraj et al, 1993; With these reservations in mind, some analogies can be drawn from the different studies. For example, catalase activity was inhibited by 20 to 30% after treatment of alfalfa nodules with 20 mM nitrate for 7 d (Becana et al, 1988), clusterbean nodules with 50 mM nitrate for 3 d (Swaraj et al, 1993), or lupin nodules with 20 mM nitrate for 4 to 6 d (Lorenzo et al, 1994). In the latter case, the nitrate-induced decline in catalase activity was associated with a decreased cytochemical staining of the enzyme in peroxisomes of infected cells (Lorenzo et al, 1990).…”

“…the larger decrease of Lb relative to total soluble protein indicates that the hemoprotein is particularly sensitive to nitrate treatment. This was also found to be the case for alfalfa and clusterbean nodules (Becana et al, 1988;Swaraj et al, 1993).…”

Modulation of symbiotic efficiency and nodular antioxidant enzyme activities in two Phaseolus vulgaris genotypes under salinity

“…In fact, APX has been shown to enhance N 2 fixation up to 4.5-fold in in vitro model system consisting of bacteria (Azorhizobium) or soybean nodules bacteroids (Ross et al 1999). The concomitant decline in the enzyme activities of the ASC-GSH pathway suggest a key link between the process of N 2 fixation and the mechanism for protection against ROS (Swaraj et al 1993). These results suggest the secondary role of APX activity to protect nodular tissues which was strongly supported by the close correlation between ARA and APX activity (r = 1) in COCOT nodules.…”

ag13 is expressed in Alnus glutinosa nodules in infected cells during endosymbiont degradation and in the nodule pericycle

“…As it has been shown before, Frankia nifH expression and plant sucrose synthase expression are switched off before Frankia vesicles start to disappear in the infected cells , van Ghelue et al 1996. In legume as well as in actinorhizal nodules, the loss of nitrogenase activity has been found to be the first symptom of senescence (Vikman et al, 1990, Swaraj et al, 1993. The loss of Frankia nifH expression has been used to mark the transition from the nitrogen fixa-tion zone to the senescence zone , These data indicate that agl3 expression might serve as a marker for the senescence zone and thus, for endosymbiont degradation in the nodule.…”