Nitric oxide signaling and cysteine protease activity in the modulation of abiotic stress responses in soybean and maize

[摘要] ABSTRACT: Nitric Oxide (NO) is an essential bioregulatory molecule in plant growth, development,and tolerance against biotic and abiotic stresses. In legume root nodules, abiotic stressesimpose restraint on metabolic capacity of bacteria and cause oxidative damage to cellularmacromolecules, leading to inhibition of nitrogenase activity. In this study, the primaryaim was to determine the influence of NO signaling on cysteine protease activity insoybean (Glycine. max [L] Merr) root nodules. Intact plants were treated with a NOdonor, diethylenetriamine/nitric oxide adjunct (DETA/NO), 8-(4-chlorophenylthio)-[CPT]-cGMP, sorbitol and sodium chloride (NaCl). The root nodule cysteine protease activitywas measured using the chromogenic substrate N-benzoil-L-p-nitroanilide (L-BAPNA).The results demonstrated NO as acting both as a protection against programmed celldeath (PCD) at low exogenously applied NO concentrations, or as inducing PCD throughregulating the cysteine proteases activity in root nodules when NO is applied at elevatedconcentrations. In the root nodules, the activity of cysteine protease is regulated eitherthrough cyclic guanosine monophosphate (cGMP)-dependent during abiotic stress orcGMP-independent pathways during normal root nodule development. The purpose ofthis research was to highlight the importance of NO in cell signaling and cysteineprotease activity in legume root nodules. We also focused on the effect of abiotic stresson two maize genotypes as well as the influence of abiotic stress on cysteine proteaseactivity in the abiotic stress-sensitive maize genotype than the tolerant genotype. Thestudy suggests that cysteine protease activity can be used as early screen to identifyabiotic stress-sensitive/tolerant maize genotype upon exposure to abiotic stress.

[发布机构] Stellenbosch University