Disease relevance of Peronospora

• However, resistances to an avirulent strain of Peronospora parasitica and avirulent and virulent strains of Pseudomonas syringae were compromised, suggesting that MPK6 plays a role in both resistance gene-mediated and basal resistance [1].

High impact information on Peronospora

• RIN4 reduction results in heightened resistance to virulent Peronospora parasitica and P. syringae, and ectopic defense gene expression [2].
• In Arabidopsis, a dominant mutant, suppressor of npr1-1, constitutive 1 (snc1), was identified previously that constitutively expresses pathogenesis-related (PR) genes and resistance against both Pseudomonas syringae pv maculicola ES4326 and Peronospora parasitica Noco2 [3].
• We describe the identification of a mutant in the Arabidopsis accession Columbia (Col-0) that exhibits enhanced downy mildew (edm1) susceptibility to several Peronospora parasitica isolates, including the RPP7-diagnostic isolate Hiks1 [4].
• In Arabidopsis ecotype Landsberg erecta (Ler), RPP5 confers resistance to the pathogen Peronospora parasitica [5].
• We cloned the RPP8 gene (for resistance to Peronospora parasitica) and compared the structure of alleles at this locus in resistant Landsberg erecta (Ler-0) and susceptible Columbia (Col-0) accessions [6].

Chemical compound and disease context of Peronospora

• The cpr5 plants were found to be constitutively resistant to two virulent pathogens, Pseudomonas syringae pv maculicola ES4326 and Peronospora parasitica Noco2; to have endogenous expression of the pathogenesis-related gene 1 (PR-1); and to have an elevated level of salicylic acid (SA) [7].

Biological context of Peronospora

• To identify components of the signal transduction pathways regulating SAR, a mutant screen was developed that uses 2,6-dichloroisonicotinic acid as an activator of SAR gene expression and pathogen resistance, followed by assays for resistance to the fungal pathogen Peronospora parasitica [8].
• We tested the ability of TIR and coiled-coil-class (also known as leucine-zipper-class) R genes to confer resistance to Pseudomonas syringae pv. tomato or Peronospora parasitica in SA-depleted (NahG) and nim1/npr1 plants [9].

Associations of Peronospora with chemical compounds

• Plants expressing the antisense gene also had high endogenous salicylic acid levels, constitutive expression of the PR-1 gene, and were resistant to Peronospora parasitica, consistent with the activation of systemic acquired resistance (SAR) [10].
• The RPP13 allele from the accession Nd-1, designated RPP13-Nd, confers resistance to five different isolates of the biotrophic oomycete, Peronospora parasitica (causal agent of downy mildew), and encodes an NBS-LRR type R protein with a putative amino-terminal leucine zipper [11].
• Thus, JA and ET sensitivity are required for cir1-mediated resistance against P. syringae pv. tomato DC3000 but not Peronospora parasitica Noco2 [12].

Gene context of Peronospora

• The pbs2 mutation also had varying effects on resistance mediated by seven different RPP (recognition of Peronospora parasitica) genes [13].
• RPP13 is a simple locus in Arabidopsis thaliana for alleles that specify downy mildew resistance to different avirulence determinants in Peronospora parasitica [11].
• In Arabidopsis, RPP4 confers resistance to Peronospora parasitica (P.p.) races Emoy2 and Emwa1 (downy mildew) [14].
• However, during infection with an avirulent oomycete, Peronospora parasitica isolate Cala-2, only NHL25 expression was reproducibly induced [15].
• This plant carries a semidominant, conditional lethal mutation that confers constitutive expression of the pathogenesis-related (PR) genes PR-1, PR-2, PR-5 and the defensin gene PDF1.2. cpr22 plants also display spontaneous lesion formation, elevated levels of salicylic acid (SA) and heightened resistance to Peronospora parasitica Emco5 [16].

References