Structure-function analysis of barley NLR immune receptor MLA10 reveals its cell compartment specific activity in cell death and disease resistance.
Plant intracellular immune receptors comprise a large number of multi-domain proteins resembling animal NOD-like receptors (NLRs). Plant NLRs typically recognize isolate-specific pathogen-derived effectors, encoded by avirulence (AVR) genes, and trigger defense responses often associated with localized host cell death. The barley MLA gene is polymorphic in nature and encodes NLRs of the coiled-coil (CC)-NB-LRR type that each detects a cognate isolate-specific effector of the barley powdery mildew fungus. We report the systematic analyses of MLA10 activity in disease resistance and cell death signaling in barley and Nicotiana benthamiana. MLA10 CC domain-triggered cell death is regulated by highly conserved motifs in the CC and the NB-ARC domains and by the C-terminal LRR of the receptor. Enforced MLA10 subcellular localization, by tagging with a nuclear localization sequence (NLS) or a nuclear export sequence (NES), shows that MLA10 activity in cell death signaling is suppressed in the nucleus but enhanced in the cytoplasm. By contrast, nuclear localized MLA10 is sufficient to mediate disease resistance against powdery mildew fungus. MLA10 retention in the cytoplasm was achieved through attachment of a glucocorticoid receptor hormone-binding domain (GR), by which we reinforced the role of cytoplasmic MLA10 in cell death signaling. Together with our data showing an essential and sufficient nuclear MLA10 activity in disease resistance, this suggests a bifurcation of MLA10-triggered cell death and disease resistance signaling in a compartment-dependent manner.
State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
Shiwei
S
Bai
Jie
J
Liu
Cheng
C
Chang
Ling
L
Zhang
Takaki
T
Maekawa
Qiuyun
Q
Wang
Wenkai
W
Xiao
Yule
Y
Liu
Jijie
J
Chai
Frank L W
FL
Takken
Paul
P
Schulze-Lefert
Qian-Hua
QH
Shen
D020816:Amino Acid Motifs; D016923:Cell Death; D060467:Disease Resistance / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D009181:Mycoses / Q000276:immunology; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013329:Structure-Activity Relationship
D010940:Plant Proteins; D018160:Receptors, Cytoplasmic and Nuclear