Identification of NB-LRR mediated nonhost resistance to wheat stripe rust in Brachypodium distachyon
J. BETTGENHAEUSER (1), M. Gardiner (1), M. Opanowicz (2), B. Gilbert (3), N. Upadhyaya (3), J. Doonan (4), M. Ayliffe (3), M. Moscou (1) (1) The Sainsbury Laboratory, United Kingdom; (2) John Innes Centre, United Kingdom; (3) CSIRO Plant Industry, Australia; (4) IBERS, Aberystwyth University, United Kingdom

The plant pathogen Puccinia striiformis f. sp. tritici (PST), comm known as wheat stripe rust, is an obligate biotroph with a wide host range. Screening 210 Brachypodium spp. accessions for macroscopic and microscopic infection symptoms identified B. distachyon as an intermediate nonhost of PST. a limited number of accessions developed symptoms and no life cycle completion was observed. The genetic architecture of resistance to three phylogenetically diverse UK PST isolates was established in a mapping population derived from two geographically diverse B. distachyon accessions. Strikingly, we discovered a relatively simple genetic architecture composed of three QTLs, designated Yrr1 to Yrr3, with isolate specificity observed to Yrr2. We confirmed the presence of all three QTLs within two additional mapping populations derived from phenotypically diverse accessions, with one new minor-effect QTL discovered. Yrr3 was fine-mapped to a 74 kb gain of function interval, which encompasses two NB-LRR type genes. While it has been proposed that nonhost and host resistance are inherently different, the genetic architecture of resistance in this nonhost system is reminiscent of a host system. The NB-LRR type candidate genes identified and isolate specificity observed suggest that the genetic architectures of host and nonhost systems are structurally coupled and share conserved components.

Abstract Number: C21-4, P19-710
Session Type: Concurrent