The Arabidopsis NADPH oxidasesRbohDandRbohFdisplay differential expression patterns and contributions during plant immunity

Abstract

Plant NADPH oxidases, also known as respiratory burst oxidase homologues (RBOHs), produce reactive oxygen species (ROS) that perform a wide range of functions. RbohD and RbohF, two of the 10 Rboh genes present in Arabidopsis, are pleiotropic and mediate diverse physiological processes including the response to pathogens. We hypothesized that the spatio-temporal control of RbohD and RbohF gene expression might be critical in determining their multiplicity of functions. Transgenic Arabidopsis plants with RbohD and RbohF promoter fusions to β-glucuronidase and Luciferase reporter genes were generated. Analysis of these plants revealed a differential expression pattern for RbohD and RbohF throughout plant development and during immune responses. RbohD and RbohF gene expression was differentially modulated by pathogen-associated molecular patterns. Histochemical stains and in vivo expression analysis showed a correlation between the level of RbohD and RbohF promoter activity, H2O2 accumulation and the amount of cell death in response to the pathogenic bacterium Pseudomonas syringae pv. tomato DC3000 and the necrotrophic fungus Plectosphaerella cucumerina. A promoter-swap strategy revealed that the promoter region of RbohD was required to drive production of ROS by this gene in response to pathogens. Moreover, RbohD promoter was activated during Arabidopsis interaction with a non-virulent P. cucumerina isolate, and susceptibility tests with the double mutant rbohD rbohF uncovered a new function for these oxidases in basal resistance. Altogether, our results suggest that differential spatio-temporal expression of the Rboh genes contributes to fine-tune RBOH/NADPH oxidase-dependent ROS production and signaling in Arabidopsis immunity.

<b><i>Salmonella</i></b> and Reactive Oxygen Species: A Love-Hate Relationship

“…As such, ROS cause damage to most, if not all, biomolecules [3, 4], including oxidation of amino acids, vitamins, lipids, nucleotides, and DNA, with damage to the later promoting mutations [5]. Indeed, deliberate production of ROS appears as a very ancient host strategy for coping with pathogens [6-11] and for acquisition of nutrients [12]. Upon contact with microbes, excessive production of ROS might also become detrimental to the host itself.…”

Redox and the circadian clock in plant immunity: A balancing act

“…Because many of these genes, such as catalases and NADPH oxidases, are also involved in plant defense, redox might add an extra layer of regulation to the clock control of plant defense[3,4]. However, ROS-dependent genes which regulate immunity are also often directly induced in the presence of the pathogen, as demonstrated by the specific spatiotemporal regulation of RBOHD and RBOHF expression during plant defense [84]. Thus, it is likely that circadian expression of these redox genes does not serve to anticipate pathogens, but rather is tied to the rhythmic metabolic ROS production as shown in [79].…”

Peroxidase-Generated Apoplastic ROS Impair Cuticle Integrity and Contribute to DAMP-Elicited Defenses

“…Their role in plant defense against a wide range of pathogens has been documented (Marino et al, 2012), however, only RBOHD appears to respond to PTI triggers (Morales et al, 2016). The RBOHD -dependent oxidative burst triggered by OG elicitors was reported to protect Arabidopsis thaliana plants from Botrytis cinerea (Galletti et al, 2008; L’Haridon et al, 2011).…”