Ancient BED-domain-containing immune receptor from wild barley confers widely effective resistance to leaf rust

Abstract

AbstractLeaf rust, caused byPuccinia hordeiis a devastating fungal disease affecting barley (Hordeum vulgaresubsp.vulgare) production globally. Race-specific resistance (R) genes have been deployed widely; however, their durability is often compromised due to the rapid emergence of virulentP. hordeiraces, prompting the search for new sources of broad-spectrum resistance. Here we report on the cloning ofRph15, a broadly effective resistance gene derived from the wild progenitorHordeum vulgaresubsp.spontaneum. We demonstrate using introgression mapping, mutation and complementation thatRph15encodes a coiled-coil nucleotide-binding leucine-rich repeat (NLR) protein with an integrated Zinc-finger BED (ZF-BED) domain. The allelic variation at theRph15locus was assessed using barley exome capture data that traced its origin to the western region of the Fertile Crescent bordering Jordan and Israel. To unravel the genetic relationship of two other leaf rust resistance genes (Rph14andRph16) mapped at similar locus on chromosome 2H, we re-sequenced theRph15gene from the near-isogenic line forRph15(Bowman+Rph15) and the two donor accessions ofRph14(PI 584760) andRph16, (PI 405292, Hs 680). Both whole genome and Sanger sequencing confirmed that Hs 680 carriedRph15, whileRph14in PI 584760 was an independent locus. A perfect diagnostic KASP marker was developed and validated to permit efficient introduction ofRph15into cultivated barley.