RTP1 encodes a novel endoplasmic reticulum (ER)‐localized protein in Arabidopsis and negatively regulates resistance against biotrophic pathogens

Abstract

SummaryOomycete pathogens cause serious damage to a wide spectrum of plants. Although host pathogen recognition via pathogen effectors and cognate plant resistance proteins is well established, the genetic basis of host factors that mediate plant susceptibility to oomycete pathogens is relatively unexplored.Here, we report on RTP1, a nodulin-related MtN21 family gene in Arabidopsis that mediates susceptibility to Phytophthora parasitica.RTP1 was identified by screening a T-DNA insertion mutant population and encoded an endoplasmic reticulum (ER)-localized protein. Overexpression of RTP1 rendered Arabidopsis more susceptible, whereas RNA silencing of RTP1 led to enhanced resistance to P. parasitica. Moreover, an RTP1 mutant, rtp1-1, displayed localized cell death, increased reactive oxygen species (ROS) production and accelerated PR1 expression, compared to the wild-type Col-0, in response to P. parasitica infection. rtp1-1 showed a similar disease response to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000, including increased disease resistance, cell death and ROS production. Furthermore, rpt1-1 exhibited resistance to the fungal pathogen Golovinomyces cichoracearum, but not to the necrotrophic pathogen Botrytis cinerea.Taken together, these results suggest that RTP1 negatively regulates plant resistance to biotrophic pathogens, possibly by regulating ROS production, cell death progression and PR1 expression.

Arabidopsis UMAMIT24 and 25 are amino acid exporters involved in seed loading

“…Previously characterized UMAMIT members include transporters localized at the plasma membrane ( Ladwig et al , 2012 ; Müller et al , 2015 ; Besnard et al , 2016 ), tonoplast ( Ranocha et al , 2010 ; Ranocha et al , 2013 ), and the ER membrane ( Pan et al , 2016 ). To determine the subcellular localization of UMAMIT24, developing seeds from plants expressing UMAMIT24promoter:UMAMIT24-GFP were imaged.…”

AtRTP5 negatively regulates plant resistance to Phytophthora pathogens by modulating the biosynthesis of endogenous jasmonic acid and salicylic acid

“…Both CBP60g , which contributes to production of SA in the presence of MAMPs (Wang et al ., 2011), and the SA response gene PR1 were up‐regulated in the absence of AtRTP5 , suggesting that the SA signalling pathway is activated in rtp5‐3 . SA plays important roles in plant resistance to Phytophthora pathogens (Pan et al , ; Sugano et al , ; Wang et al , ); therefore, we suggest that accumulated SA in rtp5‐3 contributes to plant resistance against P. parasitica .…”

“…Using the P. parasitica – A. thaliana compatible interaction system (Wang et al ., 2011b), A. thaliana T‐DNA insertion mutants (Pan et al , ; Zuo et al , ) were screened for enhanced resistance to P. parasitica . The insertion sites of the stably resistant mutants were identified by whole‐genome resequencing using uninfected detached rosette leaves of 4‐week‐old A. thaliana .…”

“…In recent years, some other susceptibility (S) genes have been identified as negative regulators of plant immunity by modifying plant hormone networks. Arabidopsis RTP1 encodes a novel endoplasmic reticulum (ER)‐localized protein and negatively regulates Arabidopsis thaliana resistance to biotrophic pathogens, possibly by affecting the transcription of salicylic acid (SA) responsive genes (Pan et al , ).…”

“…Jasmonic acid (JA) and SA are two hormones that participate in modulating the plant immunity response to different stimuli (Alazem and Lin, ). JA is required as a defence signal against necrotrophic pathogens and herbivorous insects, while SA often renders plants more resistant to biotrophic and hemibiotrophic pathogens (Cui et al , ; Pan et al , ). Activation or suppression of the JA and SA signalling pathways generally trigger expression of pathogenesis‐related (PR) genes harbouring a number of enzymatic and biological properties (Takahashi et al , ).…”