LysM Proteins TaCEBiP and TaLYK5 are Involved in Immune Responses Mediated by Chitin Coreceptor TaCERK1 in Wheat

Plant
lysin motif (LysM) ectodomain receptors interact
with pathogen-associated
molecular patterns (PAMPs) and have critical functions in plant–microbe
interactions. In this study, 65 LysM family genes were identified
using the recent version of the reference sequence of bread wheat
(Triticum aestivum), in which 23, 16,
20, and 6 members belonged to LysM-containing receptor-like kinases
(LYKs), LysM-containing receptor-like proteins (LYPs), extracellular
LysM proteins (LysMes), and intracellular nonsecretory LysM proteins
(LysMns), respectively. The study found that TaCEBiP, TaLYK5, and
TaCERK1 were highly responsive to PAMP elicitors and phytopathogens,
with TaCEBiP and TaLYK5 binding directly to chitin. TaCERK1 acted
as a coreceptor with TaCEBiP and TaLYK5 at the plasma membrane. Overexpression
of TaCEBiP, TaLYK5, and TaCERK1 in Nicotiana benthamiana leaves exhibited enhanced resistance to Sclerotinia
sclerotiorum. Subsequently, knocking down TaCEBiP, TaLYK5, and TaCERK1 genes with barley stripe mosaic virus–VIGS compromised the
wheat defense response to an avirulent strain of Puccinia
striiformis. The study concluded that wheat has two
synergistic chitin perception systems for detecting pathogen elicitors,
with the activated CERK1 intracellular kinase domain leading to signaling
transduction. This research provides valuable insights into the functional
roles and regulatory mechanisms of wheat LysM members under biotic
stress.