A LysM receptor-like kinase TaLYK5 positively regulates wheat resistance to leaf rust

Wheat leaf rust, caused by the biotrophic fungus Puccinia triticina (Pt), is one of the most destructive diseases threatening global wheat production. Lysin motif (LysM)-containing receptors play central roles in plant recognition of fungal chitin and activation of pattern-triggered immunity (PTI), but the function of the LysM receptor-like kinase TaLYK5 in wheat resistance to leaf rust remains largely unknown. Here, we show that TaLYK5 lacks conserved kinase motifs essential for catalytic activity and is predicted to be a pseudokinase, suggesting that it may function through a co-receptor to transmit chitin signals. The transcript levels of TaLYK5 were rapidly and persistently upregulated upon Pt infection and chitin treatment in wheat. Transient expression of TaLYK5-6A in Nicotiana benthamiana significantly enhanced chitin-induced callose deposition. Transient silencing of TaLYK5 in wheat compromised resistance to Pt, with reduced H₂O₂ accumulation and increased fungal colonization. Importantly, stable transgenic overexpression of TaLYK5-6A in transgenic wheat lines conferred enhanced resistance to Pt, as shown by significantly fewer uredia and lower fungal biomass. Furthermore, overexpression of TaLYK5-6A enhanced chitin-induced callose deposition and expression of PTI marker genes. Collectively, these results demonstrate that TaLYK5 positively regulates wheat resistance to leaf rust, and this regulation is associated with chitin-triggered PTI, highlighting its potential as a candidate gene for improving leaf rust resistance in wheat.