StCDPK5 confers resistance to late blight pathogen but increases susceptibility to early blight pathogen in potato via reactive oxygen species burst

Abstract

Summary• Potato (Solanum tuberosum) calcium-dependent protein kinase (StCDPK5) has been shown to phosphorylate the N-terminal region of plasma membrane RBOH (respiratory burst oxidase homolog) proteins, and participate in StRBOHB-mediated reactive oxygen species (ROS) burst. The constitutively active form, StCDPK5VK, provides a useful tool for gain-of-function analysis of RBOH in defense responses.• StCDPK5-and StCDPK5VK-green fluorescent protein fusion proteins were predominantly targeted to the plasma membrane, and conditional expression of StCDPK5VK activated StRBOHA-D. The interaction was confirmed by bimolecular fluorescence complementation assay. We generated transgenic potato plants containing StCDPK5VK under the control of a pathogen-inducible promoter to investigate the role of ROS burst on defense responses to blight pathogens.• Virulent isolates of the late blight pathogen Phytophthora infestans and the early blight pathogen Alternaria solani induced hypersensitive response-like cell death accompanied by ROS production at the infection sites of transgenic plants. Transgenic plants showed resistance to the near-obligate hemibiotrophic pathogen P. infestans and, by contrast, increased susceptibility to the necrotrophic pathogen A. solani.• These results indicate that RBOH-dependent ROS contribute to basal defense against near-obligate pathogens, but have a negative role in resistance or have a positive role in expansion of disease lesions caused by necrotrophic pathogens.

Reactive oxygen species and plant resistance to fungal pathogens

“…However, transgenic plants were more susceptible to the necrotrophic pathogen Alternaria solani. Thus, RBOH-dependent ROS participate in the defence to hemibiotrophic pathogens, but help the necrotrophic pathogen in the colonisation of the tissue (Kobayashi et al, 2012). In agreement with these data, NbRbohB-silenced N. benthamiana plants develop smaller lesions after inoculation with B. cinerea (Asai and Yoshioka, 2009).…”

“…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.…”

WRKY Transcription Factors Phosphorylated by MAPK Regulate a Plant Immune NADPH Oxidase in Nicotiana benthamiana

“…Loss-offunction analysis of BAK1, a coreceptor of PRRs, was performed to eliminate PTI signals by agroinfiltration and did not result in suppression of WRKY-triggered ROS burst ( Figure 8B). In addition, we previously reported that overexpression of RBOHs (St-RBOHA, B, C, and D) by agroinfiltration does not induce a ROS burst (Kobayashi et al, 2012;Asai et al, 2013). We speculate that certain posttranslational regulatory mechanisms, such as CDPK-mediated phosphorylation, might exist downstream of MAPK-WRKY pathway, coordinately or synergistically enhancing RBOH activity with various positive regulators during immune responses.…”

“…Our results indicated that transient expression of phospho-mimicking WRKY11 significantly induced ROS burst than MEK2 DD -mediated ROS burst, suggesting that the WRKY activates RBOHB not only at the transcriptional level, but also at the posttranslational level ( Figure 8). We reported that N termini of RBOHs (St-RBOHA, B, C, and D and Nb-RBOHA and B) are directly phosphorylated by calciumdependent protein kinase (CDPK or CPK), resulting in the activation of these RBOHs (Kobayashi et al, 2007(Kobayashi et al, , 2012Asai et al, 2013). In this study, the CDPK4 gene, which encodes an ortholog of the St-RBOH-activating potato St-CDPK4 (Kobayashi et al, 2007), was transactivated downstream of the MAPK-WRKY pathway in N. benthamiana leaves (Supplemental Figure 10).…”

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

“…Here, we report the identification and characterization of two components of a Ca 2+ signaling module also identified in this VIGS screen: a calcium sensor (calcineurin B-like protein [CBL]) and its putative target, a calcineurin B-like interacting protein kinase (CIPK). In the general context of R protein/effector signaling, few proteins that sense and relay Ca 2+ signals have been described, among them the CDPKs/CPKs, which have been shown to play a role in defense activation in different pathosystems (Boudsocq et al, 2010;Kobayashi et al, 2012;Dubiella et al, 2013). Ca 2+ -related downstream signaling events include salicylic acid synthesis, nitric oxide generation, and transcriptional gene activation (Ma et al, 2008;Du et al, 2009;Boudsocq et al, 2010;Ma et al, 2012).…”