title: TNL-mediated immunity in Arabidopsis requires complex regulation of the redundant ADR1 gene family.
abstract: Nucleotide-binding leucine-rich repeat proteins (NLRs) serve as intracellular immune receptors in animals and plants. Sensor NLRs perceive pathogen-derived effector molecules and trigger robust host defense. Recent studies revealed the role of three coiled-coil-type NLRs (CNLs) of the ADR1 family - ADR1, ADR1-L1 and ADR1-L2 - as redundant helper NLRs, whose function is required for defense mediated by multiple sensor NLRs. From a mutant snc1-enhancing (MUSE) forward genetic screen in Arabidopsis targeted to identify negative regulators of snc1 that encodes a TIR-type NLR (TNL), we isolated two alleles of muse15, both carrying mutations in ADR1-L1. Interestingly, loss of ADR1-L1 also enhances immunity-related phenotypes in other autoimmune mutants including cpr1, bal and lsd1. This immunity-enhancing effect is not mediated by increased SNC1 protein stability, nor is it fully dependent on the accumulation of the defense hormone salicylic acid (SA). Transcriptional analysis revealed an upregulation of ADR1 and ADR1-L2 in the adr1-L1 background, which may overcompensate the loss of ADR1-L1, resulting in enhanced immunity. Interestingly, autoimmunity of snc1 and chs2, which encode typical TNLs, is fully suppressed by the adr1 triple mutant, suggesting that the ADRs are required for TNL downstream signaling. This study extends our knowledge on the interplay among ADRs and reveals their complexity in defense regulation.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.|Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Oliver Xiaoou
authors.initials: OX
authors.lastname: Dong
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.|Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Meixuezi
authors.initials: M
authors.lastname: Tong
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Vera
authors.initials: V
authors.lastname: Bonardi
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Farid
authors.initials: F
authors.lastname: El Kasmi
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.|Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Virginia
authors.initials: V
authors.lastname: Woloshen
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Wünsch
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.|Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, NC, 27599-3280, USA.
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Dangl
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.|Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005820:Genetic Testing; D000090263:Leucine-Rich Repeat Proteins; D008954:Models, Biological; D005810:Multigene Family; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D057865:Plant Immunity; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D000090263:Leucine-Rich Repeat Proteins; D011506:Proteins; D020156:Salicylic Acid
keywords: ADR; ADR1; ADR1-L1; ADR1-L2; MUSE; SNC1; nucleotide-binding leucine-rich repeat (NLR) receptor; plant immunity