An Evolutionarily Conserved Mediator of Plant Disease Resistance Gene Function Is Required for Normal Arabidopsis Development

Holt, Ben F.; Boyes, Douglas C.; Ellerström, Mats; Siefers, Nicholas; Wiig, Aaron; Kauffman, Scott; Grant, Murray; Dangl, Jeffery L.

doi:10.1016/s1534-5807(02)00174-0

Cited by 115 publications

(107 citation statements)

References 52 publications

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“…A TATA-binding protein accessory factor, AtTIP49a, interacts with RPM1 and other NB-LRR proteins, and is a negative regulator of defence 97 . Two nucleoporins and importins are required for the output response of an ectopically activated NB-LRR protein 98,99 .…”

Section: Challenges and Opportunities For The Futurementioning

confidence: 99%

The plant immune system

Jones

Dangl

2006

Nature

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10,906

9,959

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Many plant-associated microbes are pathogens that impair plant growth and reproduction. Plants respond to infection using a two-branched innate immune system. The first branch recognizes and responds to molecules common to many classes of microbes, including non-pathogens. The second responds to pathogen virulence factors, either directly or through their effects on host targets. These plant immune systems, and the pathogen molecules to which they respond, provide extraordinary insights into molecular recognition, cell biology and evolution across biological kingdoms. A detailed understanding of plant immune function will underpin crop improvement for food, fibre and biofuels production.

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Section: Challenges and Opportunities For The Futurementioning

confidence: 99%

The plant immune system

Jones

Dangl

2006

Nature

Self Cite

10,906

9,959

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“…Functional overlap between pathogen-induced defense signaling and plant development has been reported (Holt et al 2002;Godiard et al 2003;Chu et al 2006), which may partly explain the fitness cost in disease resistance. Constitutive expression of an R gene sometimes results in plants with abnormal morphology or decreased fertility.…”

Section: Discussionmentioning

confidence: 99%

The Expression Pattern of a Rice Disease Resistance Gene Xa3/Xa26 Is Differentially Regulated by the Genetic Backgrounds and Developmental Stages That Influence Its Function

et al. 2007

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Genetic background and developmental stage influence the function of some disease resistance (R) genes. The molecular mechanisms of these modifications remain elusive. Our results show that the two factors are associated with the expression of the R gene in rice Xa3 (also known as Xa26)-mediated resistance to Xanthomonas oryzae pv. oryzae (Xoo), which in turn influences the expression of defenseresponsive genes. The background of japonica rice, one of the two major subspecies of Asian cultivated rice, facilitates the function of Xa3 more than the background of indica rice, another rice subspecies. Xa3 expression gradually increases from early seedling stage to adult stage. Japonica plants carrying Xa3 regulated by the native promoter showed an enlarged resistance spectrum (i.e., resistance to more Xoo races), an increased resistance level (i.e., further reduced lesion length), and whole-growth-stage resistance compared to the indica rice; this enhanced resistance was associated with an increased expression of Xa3 throughout the growth stages in the japonica plants, which resulted in enhanced expression of defenseresponsive genes. Overexpressing Xa3 with a constitutive strong promoter further enhanced rice resistance due to further increased Xa3 transcripts in both indica and japonica backgrounds, whereas regulating Xa3 with a pathogen-induced weak promoter impaired rice resistance.

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“…Hyaloperonospora arabidopsidis (Hpa) propagation and inoculation were performed as described (34). Ten-day-old cotyledons of plants were inoculated with the asexual spores of Hpa isolate Emwa1.…”

Section: Methodsmentioning

confidence: 99%

Specific Arabidopsis HSP90.2 alleles recapitulate RAR1 cochaperone function in plant NB-LRR disease resistance protein regulation

Hubert¹,

He²,

McNulty³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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100

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Both plants and animals require the activity of proteins containing nucleotide binding (NB) domain and leucine-rich repeat (LRR)domains for proper immune system function. NB-LRR proteins in plants (NLR proteins in animals) also require conserved regulation via the proteins SGT1 and cytosolic HSP90. RAR1, a protein specifically required for plant innate immunity, interacts with SGT1 and HSP90 to maintain proper NB-LRR protein steady-state levels. Here, we present the identification and characterization of specific mutations in Arabidopsis HSP90.2 that suppress all known phenotypes of rar1. These mutations are unique with respect to the many mutant alleles of HSP90 identified in all systems in that they can bypass the requirement for a cochaperone and result in the recovery of client protein accumulation and function. Additionally, these mutations separate HSP90 ATP hydrolysis from HSP90 function in client protein folding and/or accumulation. By recapitulating the activity of RAR1, these novel hsp90 alleles allow us to propose that RAR1 regulates the physical open-close cycling of a known ''lid structure'' that is used as a dynamic regulatory HSP90 mechanism. Thus, in rar1, lid cycling is locked into a conformation favoring NB-LRR client degradation, likely via SGT1 and the proteasome.innate immunity ͉ Pseudomonas syringae ͉ SGT1 ͉ STAND ATPase protein P lants have evolved a highly complex immune system centered on pathogen recognition via the evolutionarily-conserved NB-LRR proteins. Pathogen-triggered activation of NB-LRR proteins leads to several responses, including cell wall strengthening, transcriptional reprogramming, and a form of programmed cell death termed the hypersensitive response (HR). Because their function often results in cell death, proper maintenance of NB-LRR protein levels and activation state are vital to the health of the plant (1).NB-LRR proteins can be divided into 2 structural subgroups based on the presence of either a likely coiled-coil (CC) or Toll interleukin-1 receptor (TIR) domain at their N termini. Either of these N-terminal domains is followed in both subgroups by a middle nucleotide binding (NB) site and a C-terminal leucine-rich repeat (LRR). This general structure is not only conserved across all plants but extends to NOD/Caterpiller/NLR proteins that mediate various processes in mammalian innate immunity (2).Just as the domain composition of these intracellular receptors is conserved from plants to animals, so is the regulation of their steady-state accumulation. Cytosolic HSP90 and the cochaperone SGT1 have been previously demonstrated to not only be important for regulation of NB-LRR proteins in plants, but also in regulation of NLR function in animals (3). A third protein called RAR1 appears to play a role in innate immunity specifically in plants (4).All 3 of these proteins can independently interact with one another; the CS domain of SGT1b, or the CHORDI domain of RAR1, can interact with the N-terminal ATPase domain of HSP90; the CHORDII domain of RAR1 also interacts wi...

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An Evolutionarily Conserved Mediator of Plant Disease Resistance Gene Function Is Required for Normal Arabidopsis Development

Cited by 115 publications

References 52 publications

The plant immune system

The plant immune system

The Expression Pattern of a Rice Disease Resistance Gene Xa3/Xa26 Is Differentially Regulated by the Genetic Backgrounds and Developmental Stages That Influence Its Function

Specific Arabidopsis HSP90.2 alleles recapitulate RAR1 cochaperone function in plant NB-LRR disease resistance protein regulation

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