Glycolate Oxidase Modulates Reactive Oxygen Species–Mediated Signal Transduction during Nonhost Resistance in Nicotiana benthamiana and Arabidopsis  

Abstract

In contrast to gene-for-gene disease resistance, nonhost resistance governs defense responses to a broad range of potential pathogen species. To identify specific genes involved in the signal transduction cascade associated with nonhost disease resistance, we used a virus-induced gene-silencing screen in Nicotiana benthamiana, and identified the peroxisomal enzyme glycolate oxidase (GOX) as an essential component of nonhost resistance. GOX-silenced N. benthamiana and Arabidopsis thaliana GOX T-DNA insertion mutants are compromised for nonhost resistance. Moreover, Arabidopsis gox mutants have lower H 2 O 2 accumulation, reduced callose deposition, and reduced electrolyte leakage upon inoculation with hypersensitive response-causing nonhost pathogens. Arabidopsis gox mutants were not affected in NADPH oxidase activity, and silencing of a gene encoding NADPH oxidase (Respiratory burst oxidase homolog) in the gox mutants did not further increase susceptibility to nonhost pathogens, suggesting that GOX functions independently from NADPH oxidase. In the two gox mutants examined (haox2 and gox3), the expression of several defense-related genes upon nonhost pathogen inoculation was decreased compared with wild-type plants. Here we show that GOX is an alternative source for the production of H 2 O 2 during both gene-for-gene and nonhost resistance responses.

The Tomato Calcium Sensor Cbl10 and Its Interacting Protein Kinase Cipk6 Define a Signaling Pathway in Plant Immunity

“…An oxidative burst is a hallmark in nearly all plant responses to pathogen attack and plays an important signaling role in PCD (Torres, 2010). Different enzymatic sources of ROS have been described (Daudi et al, 2012;Ishiga et al, 2012;Rojas et al, 2012); however, the membrane-bound RBOH complex seems to play a central role in generating apoplastic ROS in PTI and ETI and possibly in amplifying ROS generated in different cellular compartments (Torres, 2010). The role of specific RBOH enzymes in pathogen-elicited PCD and resistance is complex, and they play distinct roles depending on the pathogen and the plant species.…”

Reactive oxygen species and plant resistance to fungal pathogens

“…DAB staining has been often used to visualise the generation of H 2 O 2 in planta (Asai et al, 2010;Dubreuil-Maurizi et al, 2010;Kobayashi et al, 2012;L'Haridon et al, 2011;Liao et al, 2012;Rojas et al, 2012;Simon et al, 2013;Torres et al, 2005;Yokawa et al, 2011;Zhang et al, 2012). The Amplex Red hydrogen peroxide/peroxidase activity assay also allows quantifying H 2 O 2 concentrations and consists in a non-fluorescent molecule that is oxidised by H 2 O 2 and becomes fluorescent in presence of peroxidase.…”

Cytoplastic Glyceraldehyde-3-Phosphate Dehydrogenases Interact with ATG3 to Negatively Regulate Autophagy and Immunity in Nicotiana benthamiana

“…Four discs of 6-mm diameter were collected per sample at the indicated time point. Leaf samples were ground, subjected to serial dilution, plated on King's B agar medium supplemented with appropriate antibiotics, and incubated at 28°C for 2 d for bacterial colony counting, as previously described (Rojas et al, 2012). For Pst DC3000-induced HR cell death assays, the leaves of GAPC-silenced and control N. benthamiana plants were inoculated with Pst DC3000 at 10 7 cfu/mL, and HR was observed at 15 hpi.…”