False brome grass, Brachypodium distachyon (L.) Beauv, has been proposed
as a new model species to bridge rice and temperate cereal crops for genomics research.
However, much basic information for this species is still lacking. In this study, six
diploid B. distachyon
(2n = 2x = 10)
accessions (Bd1-1, Bd2-3, Bd3-1, Bd18-1, Bd21 and BD29) were evaluated for their response
to infestation by two cereal aphid pests of common wheat (Triticum
aestivum L.): the greenbug, Schizaphis graminum Rondani, and the
Russian wheat aphid (RWA), Diuraphis noxia Mordvilko. Through database
mining of B. distachyon expressed sequence tag (EST) and genomic DNA
sequences, 160 EST- and 21 genomic microsatellite markers were developed and used to
evaluate genetic diversity among the B. distachyon accessions. All six
accessions were resistant to RWA biotype RWA1 but showed distinct responses to feeding by
greenbug biotypes C and E, as well as RWA2 RWAs. Although microsatellite-based genetic
diversity among different accessions was generally low, Bd1-1 and BD29 were the most
diverged from the other four lines. The genetic divergence was correlated with
geographical distances between the Brachypodium accessions. Comparison of
simple sequence repeat polymorphisms in three inbred lines (Bd2-3, Bd3-1 and Bd18-1) with
their respective original parental lines revealed no effect of inbreeding on genetic
diversity. Phylogenetic analysis suggested that Aegilops tauschii (Coss.)
Schmal., the D genome donor of common wheat, was closer to B. distachyon
than to rice. The greenbug - B. distachyon system seems
to be a model of choice for plant–aphid interaction studies in the grass
genome.