A kinase fusion protein from Aegilops longissima confers resistance to wheat powdery mildew

Many disease resistance genes have been introgressed into wheat from its
wild relatives. However, reduced recombination within the introgressed
segments hinders cloning of the introgressed genes. Here, we report the
identification of wheat powdery mildew resistance gene Pm13
originated from from Aegilops longissima using a method combining physical
mapping with radiation-induced chromosomal aberrations and transcriptome
sequencing analysis of ethyl methanesulfonate (EMS)-induced
loss-of-function mutants. Pm13 encodes a kinase fusion protein, designated
MLKL-K, with an N-terminal domain of mixed lineage kinase domain-like
protein (MLKL_NTD domain) and a C-terminal serine/threonine kinase domain
bridged by a brace. The resistance function of Pm13 is validated by
transient and stable transgenic complementation assays. Transient
over-expression analyses in Nicotiana benthamiana leaves and wheat
protoplasts reveal that the fragment Brace-Kinase122-476 of MLKL-K is
capable of inducing cell death, which is dependent on a functional kinase
domain and the three α-helices in the brace region close to the N-terminus
of the kinase domain.