A Mutation within the Leucine-Rich Repeat Domain of the Arabidopsis Disease Resistance Gene RPS5 Partially Suppresses Multiple Bacterial and Downy Mildew Resistance Genes

Abstract

Recognition of pathogens by plants is mediated by several distinct families of functionally variable but structurally related disease resistance ( R ) genes. The largest family is defined by the presence of a putative nucleotide binding domain and 12 to 21 leucine-rich repeats (LRRs). The function of these LRRs has not been defined, but they are speculated to bind pathogen-derived ligands. We have isolated a mutation in the Arabidopsis RPS5 gene that indicates that the LRR region may interact with other plant proteins. The rps5-1 mutation causes a glutamate-to-lysine substitution in the third LRR and partially compromises the function of several R genes that confer bacterial and downy mildew resistance. The third LRR is relatively well conserved, and we speculate that it may interact with a signal transduction component shared by multiple R gene pathways. INTRODUCTIONThe molecular recognition of pathogens by plants is often characterized by a gene-for-gene relationship that requires a specific plant resistance ( R ) gene and a corresponding pathogen avirulence ( avr ) gene (Flor, 1971). Genetic evidence from a wide diversity of plant pathosystems suggests that when an appropriate R-avr gene pair is present, the result is host resistance, whereas absence or inactivation of either member of the gene pair results in susceptibility of the host to the pathogen. A common explanation for the molecular basis of this gene-for-gene relationship is an elicitorreceptor model (Gabriel and Rolfe, 1990). According to this model, avr genes directly or indirectly produce an elicitor that is recognized by the corresponding R gene-encoded receptor. This molecular interaction then triggers downstream signaling events that result in the activation of plant defenses and the limitation of pathogen growth.R genes have been cloned from several plant species (reviewed in Bent, 1996; Baker et al., 1997; Hammond-Kosack and Jones, 1997). These include R genes that mediate resistance to bacterial, fungal, oomycete, viral, and nematode pathogens. Many of these R gene products share structural motifs, which indicates that disease resistance to diverse pathogens may operate through similar pathways. For example, leucine-rich repeats (LRRs) are common to most of the R genes that have been characterized (Bent et al., 1994;Jones et al., 1994;Mindrinos et al., 1994; Whitham et al., 1994; Grant et al., 1995;Lawrence et al., 1995;Song et al., 1995; Dixon et al., 1996; Anderson et al., 1997;Parker et al., 1997). LRRs have been shown to play a role in protein-protein interactions (Kobe and Deisenhofer, 1994). This fact, along with the common occurrence of LRRs in R gene proteins, has led to speculation that LRRs serve as the binding domain for the pathogen-produced elicitor (Bent, 1996; Baker et al., 1997).Despite recent work in this area, it remains to be proven that LRR-containing R gene products function as receptors. In tomato, high-affinity binding sites from intact membranes have been found for an elicitor produced by races of Cladosporium fu...

Proline Isomerization of the Immune Receptor-Interacting Protein RIN4 by a Cyclophilin Inhibits Effector-Triggered Immunity in Arabidopsis

“…Arabidopsis thaliana plants used include WT (Col-0), rps2-101C (Mindrinos et al, 1994), rin4 rps2 double mutant and rpm1 rps2 rin4 triple mutant (Kim et al, 2005), npro RPS2::RPS2-HA (Axtell and Staskawicz), rpm1 (formerly described as rps3-1 ; Bisgrove et al, 1994), rps5-2 (Warren et al, 1998), and ROC1 S58F and transgenic lines silenced for ROC1 (Ma et al, 2013). Arabidopsis plants were grown in a growth room at 20°C (night) and 24°C (day) with a 10 hr light/14 hr dark photoperiod or otherwise indicated.…”

Activation of a plant nucleotide binding-leucine rich repeat disease resistance protein by a modified self protein

“…Nicotiana benthamiana seed was obtained from D. Baulcombe. The rps5-2 and pbs1-1 Arabidopsis mutants have been described previously (Warren et al, 1998;1999). The transgenic Arabidopsis thaliana line expressing PBS1:HA was provided by Robert Dowen (Dowen et al, 2009).…”

Cytosolic HSP90 associates with and modulates the Arabidopsis RPM1 disease resistance protein

“…Transgenic Arabidopsis ecotype Columbia (Col-0) (line a11) and rpm1-1 (line a11r) containing estradiol-inducible avrRpm1 have been described in Tornero et al (2002a). Mutant lines used (all in Col-0 unless noted) were ndr1-1 (Century et al, 1997), rar1-20; a null allele, originally pbs2 (Warren et al, 1999), rar1-21 (Tornero et al, 2002b), rps2-101C (Mindrinos et al, 1994), rps5-2 (Warren et al, 1998), ecotype RLD (Hinsch and Staskawicz, 1996) as an rps4 mutant control, sgt1a (T-DNA insertion in Ws-0 ecotype; A. Takahashi and K.Shirasu, in preparation), and sgt1b (edm1-1;To Èr et al, 2002).…”