An LRR‐only protein promotes NLP‐triggered cell death and disease susceptibility by facilitating oligomerization of NLP in Arabidopsis

Abstract

Summary Necrosis‐ and ethylene‐inducing peptide 1 (Nep1)‐like proteins (NLPs) constitute a superfamily of proteins toxic to dicot plants, but the molecular basis of this toxicity remains obscure. Using quantitative trait locus (QTL) analysis we investigated the genetic variation underlying ion leakage in Arabidopsis plants elicited with MoNLP1 derived from Magnaporthe oryzae. The QTL conditioning MoNLP1 toxicity was positionally cloned and further characterized to elucidate its mode of action. MoNLP1‐triggered cell death varied significantly across > 250 Arabidopsis accessions and three QTLs were identified conferring the observed variation. The QTL on chromosome 4 was uncovered to encode a leucine‐rich repeat (LRR)‐only protein designated as NTCD4, which shares high sequence identity with a set of nucleotide‐binding LRR proteins. NTCD4 was secreted into the apoplast and physically interacted with multiple NLPs. Apoplastic NTCD4 facilitated the oligomerization of NLP, which was closely associated with toxicity in planta. The natural genetic variation causing D3N change in NTCD4 reduced the secretion efficiency of NTCD4 and the infection of Botrytis cinerea on Arabidopsis plants. These observations demonstrate that the plant‐derived NTCD4 is recruited by NLPs to promote toxicity via facilitating their oligomerization, which extends our understanding of a key step in the toxic mode of action of NLPs.

Cytotoxic activity of Nep1‐like proteins on monocots

“…In addition, the cytotoxic activity of NLPs on monocots might require the involvement of receptor proteins like the NTCD4 protein that was shown to aid in the oligomerization of NLPs and thereby promote cytolytic activity in A. thaliana (Chen et al ., 2021). Such secondary target molecules could also determine the differences in NLP sensitivity observed between onion cultivars with similar GIPC compositions.…”

“…More specifically, NLPs bind to the terminal hexose residues of GIPCs, which results in a conformational change that brings a loop with a hydrophobic amino acid residue in close contact with the plasma membrane. In Arabidopsis thaliana , NLPs were shown to oligomerize upon recruitment of an apoplastic leucine‐rich repeat protein, and the interaction of the plasma membrane and the loops of oligomerized NLPs is proposed to result in the formation of a pore with subsequent cytoplasmic leakage, ultimately causing cell death (Lenarčič et al ., 2017; Chen et al ., 2021). In dicot plants, GIPCs possess two terminal hexoses (series A), whereas in monocot plants they contain three hexoses (series B) (Cacas et al ., 2013).…”

Stemphylium lycopersici Nep1-like Protein (NLP) Is a Key Virulence Factor in Tomato Gray Leaf Spot Disease

“…NLPs are taxonomically widespread in fungi, oomycetes, and bacteria [ 49 , 50 ]. The NLP family exhibits functional diversity, as demonstrated by the genetic manipulation of NLPs in many microorganisms including F. oxysporum [ 15 ], B. cinerea [ 17 ], Magnaporthe oryzae [ 51 ], B. elliptica [ 52 ], and Diplodia seriata [ 53 ].…”

The Rice Malectin Regulates Plant Cell Death and Disease Resistance by Participating in Glycoprotein Quality Control

“…The CDSs of OsMLD1 , OsRpn1 , OsSERK1 , and OsSERK2 were amplified and inserted into the pCG1301 vector to fuse in-frame with the green fluorescent protein (GFP) coding sequence, generating the 35S:OsMLD1-GFP, 35S:OsRpn1-GFP, 35S:OsSERK1-GFP, and 35S:OsSERK2-GFP fusion constructs. The expression constructs, together with mCherry-tagged organelle markers [ 94 ], were co-introduced into rice protoplasts as described previously [ 22 ]. The transformed cells were observed and photographed 16 h after infiltration through a confocal microscope (Leica TCS SP8).…”