A Dual NLR with an integrated sensory domain, complexes with a transcription factor to mediate Ug99 resistance in barley
S. SOLANKI (1), G. Ameen (1), R. Brueggeman (1) (1) North Dakota State University, U.S.A.

The barley rpg4/Rpg5 locus harbors three genes required for resistance (Rpg5, HvRga1 and HvAdf3). This resistance locus was shown to provide resistance against wheat stem rust races including Ug99. Rpg5 and HvRga1 are typical NLR proteins, however, Rpg5 has an additional kinase domain that may represent an integrated sensory domain. Microscopy data shows a strong ETI response 48HPI suggesting post haustorial resistance, yet HvAdf3 expression indicates an early prehaustorial pathogen recognition event manifested as HvAdf3 down regulation in resistant lines and early upregulation in susceptible lines at 6 HPI. Expression analysis of the NLR’s suggests that they may be co-regulated and show a subtle down-regulation of both at 24 HPI. Thus, this pathosystem may integrate both PTI and ETI components. To investigate further, we screened a 48 HPI cDNA Y2H-prey library using RPG5-PK as bait. HvVOZ1, a putative one-zinc-finger transcription factor was identified. Interestingly, HvVOZ1 was also shown to interact with the HvRga1 and Rpg5 LRR domains suggesting that it may act as a scaffold to hold the R-protein complex together. RNAi and a heterologous expression system are being used to validate these interactions in-planta. We hypothesize that the RPG5-PK domain acts as integrated sensory domain and a complex of the NLRs and HvVOZ1 regulates ETI signaling until Avr-r45 manipulation. 

Abstract Number: P17-616
Session Type: Poster