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Functional analysis of chimeric lysin motif domain receptors mediating Nod factor‐induced defense signaling in A rabidopsis thaliana and chitin‐induced nodulation signaling in L otus japonicus
Author(s) -
Wang Wei,
Xie ZhiPing,
Staehelin Christian
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12450
Subject(s) - nod factor , lotus japonicus , biology , elicitor , microbiology and biotechnology , ectodomain , chitin , signal transduction , receptor , lysin , mutant , biochemistry , gene , genetics , rhizobia , escherichia coli , chitosan , symbiosis , bacteriophage , bacteria
Summary The expression of chimeric receptors in plants is a way to activate specific signaling pathways by corresponding signal molecules. Defense signaling induced by chitin from pathogens and nodulation signaling of legumes induced by rhizobial N od factors ( NF s) depend on receptors with extracellular lysin motif ( L ys M ) domains. Here, we constructed chimeras by replacing the ectodomain of chitin elicitor receptor kinase 1 ( A t CERK 1) of A rabidopsis thaliana with ectodomains of NF receptors of L otus japonicus (Lj NFR 1 and Lj NFR 5). The hybrid constructs, named Lj NFR 1–At CERK 1 and Lj NFR 5–At CERK 1 , were expressed in cerk1‐2 , an A . thaliana CERK 1 mutant lacking chitin‐induced defense signaling. When treated with NF s from R hizobium sp. NGR 234, cerk1‐2 expressing both chimeras accumulated reactive oxygen species, expressed chitin‐responsive defense genes and showed increased resistance to F usarium oxysporum . In contrast, expression of a single chimera showed no effects. Likewise, the ectodomains of L j NFR 1 and Lj NFR 5 were replaced by those of O s CERK 1 ( Oryza sativa chitin elicitor receptor kinase 1) and O s CEB iP ( O . sativa chitin elicitor‐binding protein), respectively. The chimeras, named O s CERK 1– L j NFR 1 and O s CEB i P – L j NFR 5 , were expressed in L . japonicus NF receptor mutants ( nfr1‐1 ; nfr5‐2 ) carrying a GUS (β‐glucuronidase) gene under the control of the NIN (nodule inception) promoter. Upon chitin treatment, GUS activation reflecting nodulation signaling was observed in the roots of NF receptor mutants expressing both chimeras, whereas a single construct was not sufficient for activation. Hence, replacement of ectodomains in L ys M domain receptors provides a way to specifically trigger NF ‐induced defense signaling in non‐legumes and chitin‐induced nodulation signaling in legumes.