Enhanced disease resistance caused by BRI1 mutation is conserved between Brachypodium distachyon and barley (Hordeum vulgare)

This study investigated the impact of brassinosteroid (BR)-insensitive 1 (BRI1) mutation, the main receptor of BR in both Brachypodium distachyon and barley, on disease resistance against a range of fungal pathogens of cereals exhibiting different trophic lifestyles. Results presented here show that i) disruption of BRI1 has pleiotropic effects on disease resistance in addition to affecting plant development. BR signaling functions antagonistically with mechanisms of disease resistance that are effective against a broad range of cereal pathogens. ii) Disruption of BRI1 results in increased disease resistance against necrotrophic and hemibiotrophic pathogens that exhibit only a marginal asymptomatic phase but has no effect on biotrophic pathogens or those with a prolonged asymptomatic phase, and iii) disruption of BRI1 has a similar effect on disease resistance in B. distachyon and barley, indicating that defense mechanisms are conserved between these species. This work presents the first evidence for conservation of disease resistance mechanisms between the model species B. distachyon and the cereal crop barley and validates B. distachyon for undertaking model-to-crop translation studies of disease resistance.