The Phytophthora parasitica RXLR effector Penetration‐Specific Effector 1 favours Arabidopsis thaliana infection by interfering with auxin physiology

Abstract

Summary Pathogenic oomycetes have evolved RXLR effectors to thwart plant defense mechanisms and invade host tissues. We analysed the function of one of these effectors (Penetration‐Specific Effector 1 (PSE1)) whose transcript is transiently accumulated during penetration of host roots by the oomycete Phytophthora parasitica. Expression of PSE1 protein in tobacco (Nicotiana tabacum and Nicotiana benthamiana) leaves and in Arabidopsis thaliana plants was used to assess the role of this effector in plant physiology and in interactions with pathogens. A pharmacological approach and marker lines were used to charcterize the A. thaliana phenotypes. Expression of PSE1 in A. thaliana led to developmental perturbations associated with low concentrations of auxin at the root apex. This modification of auxin content was associated with an altered distribution of the PIN4 and PIN7 auxin efflux carriers. The PSE1 protein facilitated plant infection: it suppressed plant cell death activated by Pseudomonas syringae avirulence gene AvrPto and Phytophthora cryptogea elicitin cryptogein in tobacco and exacerbated disease symptoms upon inoculation of transgenic A. thaliana plantlets with P. parasitica in an auxin‐dependant manner. We propose that P. parasitica secretes the PSE1 protein during the penetration process to favour the infection by locally modulating the auxin content. These results support the hypothesis that effectors from plant pathogens may act on a limited set of targets, including hormones.

Transcriptome dynamics of Arabidopsis thaliana root penetration by the oomycete pathogen Phytophthora parasitica

“…Hence, six of the 14 sequences encoding RXLR effectors present on the oligoarray were present in cluster I. One of these six sequences corresponded to the PSE1 effector, which has recently been demonstrated to contribute to P. parasitica pathogenicity [38]. The expression patterns of sequences encoding cytoplasmic (RXLR and CRN) effectors are presented in Figure 3B.…”

“…These authors suggested a relay between these successive waves, interfering with plant immunity at various levels. We have shown that the PSE1 effector, which is transiently expressed during penetration, can interfere with auxin physiology to facilitate plant infection [38]. Additional functional analyses of effectors transiently expressed during the onset of infection are required to determine whether this specific set of proteins plays a particular role in modulating plant development.…”

Phytophthora parasitica: a model oomycete plant pathogen

“…Recently, a RXLR effector of P. parasitica PSE1, identified in a cDNA library for the penetrating stage of P. parasitica (Kebdani et al 2010), was proved to favor the pathogen infection by modulating the auxin accumulation during the penetration process (Evangelisti et al 2013). …”

Phytophthora infestans RXLR effector AVR1 interacts with exocyst component Sec5 to manipulate plant immunity

“…P. sojae AVR3b, which has NADH and ADP-ribose pyrophosphorylase activity, manipulates host immunity by interfering with effector-triggered immunity (Dong et al, 2011). The Phytophthora parasitica RXLR effector PENETRATION-SPECIFIC EFFECTOR1 promotes colonization by impeding host auxin physiology (Evangelisti et al, 2013). The P. infestans RXLR effector IPI-O1 disrupts the integrity of adhesions between the plasma membrane and the cell wall and uses the membrane-spanning lectin receptor kinase LecRK-I.9 as a host target (Bouwmeester et al, 2011).…”