300
ploid crested wheatgrass, Agropyron cristatum (Table 11.1 ), which, besides genes
for disease resistance and stress tolerance, was shown to harbour genes/QTL able to
enhance wheat yield performance. Already in addition lines (Wu et al. 2006 ; Han
et al. 2014 ; see Sect. 11.3.2 ), and, in translocations lines later obtained (Luan et al.
2010 ), several useful genes were allocated to A. cristatum chromosome 6P; Song
et al. 2013 ; Ye et al. 2015 ). In particular, genes/QTL enhancing relevant traits such
as number of fertile tillers and of grains per spike could be ascribed to specifi c 6P
subregions, and were expressed in translocation lines with minimal amount of 6P
chromatin (Luan et al. 2010 ; Ye et al. 2015 ). Precise characterization of these lines,
including identifi cation of 6P-specifi c markers, provides a good basis for the utiliza-
tion of multiple A. cristatum genes in wheat improvement.
The same applies to a highly effective stripe rust resistance gene present on chro-
mosome arm 3NsS of Psathyrostachys huashanica (Table 11.1 ), an endemic and
endangered wild species in China, stably transferred onto wheat arm 3BS (Kang
et al. 2011 ). The 3BL.3BS-3NsS translocation had a spontaneous occurrence in the
selfed progeny of a 3Ns monosomic addition line into wheat. Of spontaneous occur-
rence were also numerous translocations detected in advanced backcross/selfed
generations from a T. aestivum x Elymus repens cross, several of which fully
expressed the high FHB resistance of the wild parent (Zeng et al. 2013b ).
11.4 Concluding Remarks and Future Prospects
The examples above illustrated provide ample evidence of the richness of perennial
Triticeae gene pools in benefi cial traits for wheat improvement. Recent progress has
also been described for many such traits in the path of their stable incorporation into
the wheat genome, and, hence, of their well advanced “state of art” in view of prac-
tical exploitation as novel breeding materials. Although the history of distant
hybridization involving this large group of wheat relatives goes back to the 1930s
(Tsitsin 1960 ), the major progress, as, indeed, for wheat relatives in general, is con-
centrated in the very last years, in parallel with remarkable advancements in the
amount of information and tools for Triticeae genomics and related fi elds of knowl-
edge. Not only these extraordinary developments have speeded up and made much
more effective characterization and selection procedures, but also have considerably
increased the ability to capture novel variability for much more complex traits, e.g.,
yield-related traits, than those almost exclusively targeted in past years. Thus, the
answer is now ready to Cox’s question of some years ago (Cox 1997 ), concerning
the perspectives for deepening the wheat primary gene pool. He, in fact, while
appreciating the fact that “humans have resorted to interspecifi c crossing to improve
wheat’s pest resistance,” at the same time wondered “...why should wheat’s pro-
genitors not be regarded as sources of useful genetic variation for all economic
traits?” The rather obvious answer is in the above statements, that is to say we now
can manipulate genomes with knowledge and tools virtually inconceivable just a
few years ago. As a result, also the overall success of cytogenetic strategies in fi nely
C. Ceoloni et al.