Among the four cryptic species in the P. oryzae/grisea
species complex, P. oryzae and P. pennisetigena were
recognized by Rmo2 or another gene at the vicinity of this
locus, while P. grisea (Nga et al. 2012) and Pyricularia sp.
(LS) were not. If the resistance of barley to the cryptic
species were conditioned by broad-spectrum resistance
genes like Lr34 or Lr67, such cryptic-species-specific differential
reactions would not occur. If it is conditioned by
gene-for-gene interactions like in the case of Cf genes and
Rpi-blb2, such differential reactions can be explained by
the presence/absence of avirulence genes in each cryptic
species. We suggest that gene-for-gene interactions
underlie the resistance of barley to cryptic species of
Pyricularia. If Rmo2 is actually effective against P. pennisetigena,
the differential reactions of barley to P. oryzae/
P. pennisetigena and P. grisea/Pyricularia sp. (LS) might
be explained by the possible correspondence of the Rmo2
locus to an avirulence gene shared by P. pennisetigena and
P. oryzae which could be absent in the other two Pyricularia
species.