Genome-assisted identification of wheat leaf rust resistance gene Lr30 (synonym Lr.ace-4A)

Leaf rust is a devastating fungal disease of wheat. Planting resistant wheat cultivars is the most effective strategy to mitigate this threat. Here, we generate a 10.51-gigabase chromosome-scale assembly of the durum wheat landrace PI 192051. Using mutagenesis and transcriptome sequencing, we identify the leaf rust resistance gene Lr.ace-4A within a recombination-sparse region of PI 192051 and demonstrate that Lr.ace-4A is identical to the previously designated Lr30 gene in hexaploid wheat. Lr30 / Lr.ace-4A encodes a non-canonical coiled-coil nucleotide-binding leucine-rich repeat receptor, featuring tandem NB-ARC domains. This gene proves both necessary and sufficient to confer resistance to Puccinia triticina , as demonstrated by CRISPR/Cas9-induced mutations and transgenic complementation. Lr30 provides near-immunity resistance in durum wheat, though its effectiveness is diminished in hexaploid wheat. Two amino acid polymorphisms differentiate the resistant and susceptible Lr30 haplotypes, with transgenic plants carrying either variant exhibiting susceptibility. Cloning of Lr30 will accelerate its deployment in wheat breeding programs.