An extracellular Zn‐only superoxide dismutase from Puccinia striiformis confers enhanced resistance to host‐derived oxidative stress

Abstract

Accumulation of reactive oxygen species (ROS) following plant-pathogen interactions can trigger plant defence responses and directly damage pathogens. Thus, it is essential for pathogens to scavenge host-derived ROS to establish a parasitic relationship. However, the mechanisms protecting pathogens from host-derived oxidative stress remain unclear. In this study, a superoxide dismutase (SOD) gene, PsSOD1, was cloned from a wheat-Puccinia striiformis f. sp. tritici (Pst) interaction cDNA library. Transcripts of PsSOD1 were up-regulated in the early infection stage. Heterologous mutant complementation and biochemical characterization revealed that PsSOD1 encoded a Zn-only SOD. The predicted signal peptide was functional in an invertase-mutated yeast strain. Furthermore, immunoblot analysis of apoplastic proteins in Pst-infected wheat leaves and bimolecular fluorescence complementation suggested that PsSOD1 is a secreted protein that potentially forms a dimer during Pst infection. Overexpression of PsSOD1 enhanced Schizosaccharomyces pombe resistance to exogenous superoxide. Transient expression of PsSOD1 in Nicotiana benthamiana suppressed Bax-induced cell death. Knockdown of PsSOD1 using a host-induced gene silencing (HIGS) system reduced the virulence of Pst, which was associated with ROS accumulation in HIGS plants. These results suggest that PsSOD1 is an important pathogenicity factor that is secreted into the host-pathogen interface to contribute to Pst infection by scavenging host-derived ROS.

TaARPC3, Contributes to Wheat Resistance against the Stripe Rust Fungus

“…Genomic DNA were performed using the CTAB method (Del et al, 1989) from samples collected at 120 hpi after infected with Pst . Standard curve was generated by the plasmid carried the fragment of PsEF1 and TaEF1 as described (Liu J. et al, 2016; Liu P. et al, 2016) (Supplementary Table S3). …”

PSTha5a23, a candidate effector from the obligate biotrophic pathogen Puccinia striiformis f. sp. tritici, is involved in plant defense suppression and rust pathogenicity

“…To measure fungal biomass in infected wheat leaves, relative quantification of the single-copy target genes PsEF1 (from Pst) and TaEF1 (from wheat) by qRT-PCR was carried out as previously described (Panwar et al, 2013;Liu et al, 2016b). Genomic DNA of pEDV6:eGFP-or pEDV6:PSTha5a23-inoculated wheat plants was isolated using the CTAB method as previously described (Zhan et al, 2014).…”

A novel citrate synthase isoform contributes infection and stress resistance of the stripe rust fungus

“…To test whether the sporulation phenotypes observed were correlated with mycelial growth in the host tissues, fungal biomass was measured using the BSMV:PsCS1inoculated leaves superinfected with Pst. Total DNA was extracted and the relative levels of PsEF1 (the Pst gene) and TaEF-1a (the wheat gene) were calculated using real-time quantitative PCR on basis of the standard curves constructed (Liu et al, 2016). At 15 dpi, there was no significant difference in the fungal biomass between the PsCS1-silenced wheat plants and the BSMV:γinoculated controls (Supporting Information Fig.…”

“…Total RNA extraction and cDNA synthesis were performed as previously described (Liu et al, 2014). The expression levels of PsCS1 were assayed at different Pst infection stages by qRT-PCR as previously described (Liu et al, 2016). The gene expression in Pst was normalized using elongation factor-1 (EF-1) as an internal reference (Yin et al, 2009).…”

“…The Western blot analysis was performed as previously described (Liu et al, 2016). The purified fusion proteins were recognized by anti-His mouse monoclonal antibody and the nitrocellulose membrane was immunostained with diaminobenzidine (DAB) for 10 min in the dark.…”