Wheat leaf rust resistance gene Lr13 is a specific Ne2 allele for hybrid necrosis

Wheat gene Lr13 confers resistance to leaf rust caused by Puccinia triticina. The gene resides in the proximal region of chromosome 2BS and is pleiotropic with, or strongly linked to, the Ne2m allele, causing hybrid necrosis in crosses carrying complementary locus Ne1 alleles on chromosome 5BL. A nucleotide-binding leucine-rich repeat (NLR) immune receptor-encoding gene was isolated following mutagenesis and resistance (R) gene enrichment and sequencing (MutRenSeq). Genetic segregation, virus induced gene silencing, comparative genomics, and analysis of lr13 mutants, which had also been shown to have lost the necrosis-inducing function of Ne2m, strongly support the identity of a single Lr13/Ne2m gene. This implicates immune system dysfunction as the cause hybrid necrosis in wheat hybrids combining the epistatic alleles at the Ne2 and Ne1 loci.