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Autoimmunity and effector recognition in Arabidopsis thaliana can be uncoupled by mutations in the RRS1‐R immune receptor
Author(s) -
Newman Toby E.,
Lee Jungmin,
Williams Simon J.,
Choi Sera,
Halane Morgan K.,
Zhou Jun,
Solomon Peter,
Kobe Bostjan,
Jones Jonathan D. G.,
Segonzac Cécile,
Sohn Kee Hoon
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15617
Subject(s) - pseudomonas syringae , effector , biology , arabidopsis , genetics , arabidopsis thaliana , complementation , ralstonia solanacearum , plant immunity , immune receptor , r gene , mutant , gene , plant disease resistance , microbiology and biotechnology , receptor , pathogen
Summary Plant nucleotide‐binding leucine‐rich repeat ( NLR ) disease resistance proteins recognize specific pathogen effectors and activate a cellular defense program. In Arabidopsis thaliana (Arabidopsis), Resistance to Ralstonia solanacearum 1 ( RRS 1‐R) and Resistance to Pseudomonas syringae 4 ( RPS 4) function together to recognize the unrelated bacterial effectors PopP2 and AvrRps4. In the plant cell nucleus, the RRS 1‐R/ RPS 4 complex binds to and signals the presence of AvrRps4 or PopP2. The exact mechanism underlying NLR signaling and immunity activation remains to be elucidated. Using genetic and biochemical approaches, we characterized the intragenic suppressors of sensitive to low humidity 1 ( slh1 ), a temperature‐sensitive autoimmune allele of RRS 1‐R . Our analyses identified five amino acid residues that contribute to RRS 1‐ R SLH 1 autoactivity. We investigated the role of these residues in the RRS 1‐R allele by genetic complementation, and found that C15 in the Toll/interleukin‐1 receptor ( TIR ) domain and L816 in the LRR domain were also important for effector recognition. Further characterization of the intragenic suppressive mutations located in the RRS 1‐R TIR domain revealed differing requirements for RRS 1‐R/ RPS 4‐dependent autoimmunity and effector‐triggered immunity. Our results provide novel information about the mechanisms which, in turn, hold an NLR protein complex inactive and allow adequate activation in the presence of pathogens.