Plasma membrane-localized immune receptors play a pivotal role in plant disease resistance by sensing conserved Pathogen-Associated Molecular Patterns (PAMPs) and activate immune responses. How PAMPs activate these receptors has been unknown. One such receptor is designated CHITIN ELICITOR RECEPTOR KINASE 1 （CERK1）, which specifically perceives chitin, a fungal cell wall component.

A joined team led by Professor Jian-Min Zhouof the Institute of Genetics and Developmental Biology, CASand Professor Jijie Chai of Tsinghua University discovered that chitin rapidly induces a dimerization of CERK1, leading to CERK1 phosphorylation and activation of the downstream signaling pathway. Abrogation of such dimerization results in a blockage of immune signaling. The team also solved the structure of a CERK1-chitin complex, uncovering themechanism by which the receptor binds chitin.

The work was published online in Science on June1, 2012 (336：1160-1164). Professor Jijie Chai of Tsinghua University, Professor Jian-Min Zhou of the Institute of Genetics and Developmental Biology, CAS, and Professor Junbiao Chang of Zhengzhou University are co-corresponding authors of the paper. Graduate students Tingting Liu from Tsinghua University and Zixu Liu from Nanjing University are co-first authors on the paper. This work was supported by grants from the Chinese Ministry of Science and Technology.

（Image by Jianmin Zhou, et al）

Left：Tight packing of the three LysMs in AtCERK1-ECD;

Middle：Chitin induces dimerization of the full-length AtCERK1 protein in protoplasts .

Chitin induces AtCERK1-ECD dimerization in protoplasts.

Right：(NAG)5 inhibits (NAG)8-induced H2O2 production in planta.