Lysin motif (LysM)-containing proteins are important pattern recognition
receptors (PRRs) in plants, which function in the perception of
microbe-associated molecular patterns (MAMPs) and in the defense against
pathogenic attack. To date, the LysM genes have not been fully analyzed in
cotton (Gossypium hirsutum) or effectively utilized for disease resistance.

The team of Jun Xu from Nanjing Agricultural University in China identified
all LysM genes from four sequenced cotton species. These LysM genes were
then classified into four groups with different structural characteristics
and a variety of expression patterns in different organs and tissues when
induced by chitin or Verticillium dahliae. The team then focused on three
genes, Lyp1, Lyk7, and LysMe3, which showed a significant increase in
expression in response to chitin signals, V. dahliae presence, and several
stress-related signaling compounds.

Lyp1, Lyk7, and LysMe3 proteins were found to be localized to the plasma
membrane. Silencing of their expression in cotton drastically impaired
salicylic acid, jasmonic acid, and reactive oxygen species generation. The
silencing also impaired defense gene activation and compromised resistance
to V. dahliae.

These results indicate that Lyp1, Lyk7, and LysMe3 are important PRRs that
function in the recognition of chitin signals to activate the downstream
defense processes and induce cotton defense against V. dahliae.

[bmcplantbiol.biomedcentral.com]