ARS | Publication request: Brachypodium as a model for unraveling stem rust resistance

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 16, 2011
Publication Date: October 19, 2011
Citation: Garvin, D.F. 2011. Brachypodium as a model for unraveling stem rust resistance [abstract]. 1st European Brachypodium Workshop, October 19-21, 2011, Versailles, France. p. 68.

Technical Abstract: Members belonging to the fungal genus Puccinia are highly destructive to cool season cereal crops. Of particular concern is P. graminis, the causal agent of stem rust, which poses a threat to wheat production globally due to the emergence of new races that defeat previously effective resistance genes. Unlike Arabidopsis, Brachypodium distachyon (Brachypodium) is reported to serve as a host to Puccinia species, and thus it may be a valuable surrogate for exploring Brachypodium-rust pathosystems. We have found that Brachypodium can be colonized by different formae specialis of P. graminis and that natural variation for resistance resides in Brachypodium germplasm. Genetic analysis of resistance to timothy stem rust, P. graminis phlei-pratensis, in one recombinant inbred population suggests major gene control, and efforts are underway to isolate this gene. Similarly, there is significant variation for resistance to wheat stem rust (P. graminis tritici). However, unlike timothy stem rust reactions, the disease phenotypes here are highly diverse, suggesting that the resistance may be quantitative in nature. We hypothesize that some of this broad variation may reflect minor gene variation associated with non-host resistance. Screens of mutant populations have identified validated genotypes both with increased susceptibility and with enhanced resistance, and genetic studies are ongoing to further explore their biological basis.