A secreted catalase contributes to Puccinia striiformis resistance to host-derived oxidative stress

Abstract

Plants can produce reactive oxygen species (ROS) to counteract pathogen invasion, and pathogens have also evolved corresponding ROS scavenging strategies to promote infection and pathogenicity. Catalases (CATs) have been found to play pivotal roles in detoxifying H2O2 formed by superoxide anion catalyzed by superoxide dismutases (SODs). However, few studies have addressed H2O2 removing during rust fungi infection of wheat. In this study, we cloned a CAT gene PsCAT1 from Puccinia striiformis f. sp. tritici (Pst), which encodes a monofunctional heme-containing catalase. PsCAT1 exhibited a high degree of tolerance to pH and temperature, and forms high homopolymers.Heterologous complementation assays in Saccharomyces cerevisiae reveal that the signal peptide of PsCAT1 is functional. Overexpression of PsCAT1 enhanced S. cerevisiae resistance to H2O2. Transient expression of PsCAT1 in Nicotiana benthamiana suppressed Bax-induced cell death. Knockdown of PsCAT1 using a host-induced gene silencing (HIGS) system led to the reduced virulence of Pst, which was correlated to H2O2 accumulation in HIGS plants. These results indicate that PsCAT1 acts as an important pathogenicity factor that facilitates Pst infection by scavenging host-derived H2O2.

Antioxidant Systems of Plant Pathogenic Fungi: Functions in Oxidative Stress Response and Their Regulatory Mechanisms

“…Deletion of each monofunctional catalase-encoding gene did not result in a phenotypic difference compared to the wild-type strain in F. graminearum ( Lee et al, 2018 ), while the transcript levels of all five catalases significantly increased upon H 2 O 2 treatment ( Lee et al, 2014 ), suggesting their redundant functions in the oxidative stress response. Among the identified typical catalases, PsCAT1 of P. striiformi , SsCAT1 and SsCAT2 of S. sclerotiorum , and CATB of Magnaporthe oryzae are required for fungal virulence ( Huang et al, 2021 ; Skamnioti et al, 2007 ; Yarden et al, 2014 ; Yuan et al, 2021b ). PsCAT1 and SsCAT2 are responsible for resistance to oxidative stress and it was confirmed that the deletion of both genes caused H 2 O 2 accumulation in host plant cells, indicating that two catalases are important for scavenging host-derived ROS.…”