CatB is Critical for Total Catalase Activity and Reduces Bactericidal Effects of Phenazine-1-Carboxylic Acid on Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola

Abstract

Rice bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae, and rice bacterial leaf streak, caused by X. oryzae pv. oryzicola, are major diseases of rice. Phenazine-1-carboxylic acid (PCA) is a natural product that is isolated from Pseudomonas spp. and is used to control many important rice diseases in China. We previously reported that PCA disturbs the redox balance, which results in the accumulation of reactive oxygen species in X. oryzae pv. oryzae. In this study, we found that PCA significantly upregulated the transcript levels of catB and katE, which encode catalases, and that PCA sensitivity was reduced when X. oryzae pvs. oryzae and oryzicola were cultured with exogenous catalase. Furthermore, catB deletion mutants of X. oryzae pvs. oryzae and oryzicola showed dramatically decreased total catalase activity, increased sensitivity to PCA, and reduced virulence in rice. In contrast, deletion mutants of srpA and katG, which also encode catalases, exhibited little change in PCA sensitivity. The results indicate that catB in both X. oryzae pvs. oryzae and oryzicola encodes a catalase that helps protect the bacteria against PCA-induced stress.

Crucial role of oxidative stress in bactericidal effect of parthenolide against Xanthomonas oryzae pv. oryzae

“…We also found that exogenous CAT dramatically reduced anti‐bacterial activity of PTL, and 100 U mL −1 of exogenous CAT almost fully abolished its anti‐bacterial effect, suggesting that ROS is critical in the bactericidal effect of PTL. This result is also similar to PCA . To further confirm the relationship between CAT and the bactericidal effect of PTL, we tested PTL sensitivity of CAT deletion mutants of Xoo , and found that PTL sensitivity of these mutants significantly increased compared with that of wild‐type Xoo strain.…”

“…Xoo strains include ZJ173, ΔZ/ catB , ΔZ/ katE , and ΔZ/ srpA . ΔZ/ catB , ΔZ/ katE , and ΔZ/ srpA are CAT deletion mutants generated from wild‐type Xoo strain ZJ173 . Bacterial cells were grown at 28 °C in nutrient broth (NB) medium in conical flasks with shaking at 175 rpm.…”

“…PTL and hydrogen peroxide (H 2 O 2 ) sensitivity of Xoo strains (ZJ173, ΔZ/ catB , ΔZ/ katE , and ΔZ/ srpA ) were observed as described previously . In brief, bacterial strains were cultured to logarithmic growth phase, and the OD 600 values of bacterial suspensions were adjusted to 1.0.…”

“…ΔZ/catB, ΔZ/katE, and ΔZ/srpA are CAT deletion mutants generated from wild-type Xoo strain ZJ173. 23 Bacterial cells were grown at 28 ∘ C in nutrient broth (NB) medium in conical flasks with shaking at 175 rpm. NB medium was composed of 3 g L −1 beef extract, 5 g L −1 polypeptone, 1 g L −1 yeast extract, and 10 g L −1 sucrose, and the pH was adjusted to 7.0 with 1 M sodium hydroxide.…”

A proper PiCAT2 level is critical for sporulation, sporangium function, and pathogenicity of Phytophthora infestans

“…Together with superoxide dismutase and glutathione peroxidase, catalase plays a vital role in the antioxidant systems that protect against the adverse effects of free radicals (Blackman and Hardham, 2008;Ighodaro and Akinloye, 2018). Many studies have confirmed that catalase is required for the growth, development, and pathogenesis of various organisms (Wysong et al, 1998;Schriner et al, 2005;Pan et al, 2017;Wang et al, 2019).…”