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they are characterized by an intermediate flow-
ering time (in comparison to winter and spring
types) when grown under inductive photoperi-
ods in the absence of vernalization (Cockram
et al. 2009), while von Zitzewitz and colleagues
(2005) classified them simply as cold-tolerant
and vernalization unresponsive.
The vernalization requirement has therefore
probably been the most important adaptative trait
driving the differentiation of the cultivated gene
pools of Triticeae throughout the world. Begin-
ning with the Industrial Revolution, traditional
agricultural systems were replaced by modern
methods, and landraces by modern cultivars. At
the beginning of the twentieth century the first
pure-line varieties were released, and dwarfism
genes were first introgressed into bread wheat
by N. Strampelli in Italy (Borojevic and Boroje-
vic 2005). Selection led however to a profound
narrowing of the genetic basis of crops, leav-
ing behind many potentially useful genes, as
demonstrated by molecular marker techniques
(Tanksley and McCouch 1997). Investigation of
the nucleotide diversity in a sample of acces-
sions corresponding to different stages in wheat
evolution showed a strong diversity reduction
of domesticated T. dicoccum (-70%), durum (-
84%) and bread wheats (-69%), with respect to
the wild T. dicoccoides (Haudry et al. 2007).
In barley, molecular studies showed that only
40% of alleles found in the wild progenitor
Hordeum vulgare ssp. spontaneum could be still
found in cultivated genotypes (Ellis et al. 2000).
These findings are not surprising, if we consider
that the majority of barley 6-row winter vari-
eties grown in Europe were developed from only
five progenitors (Cockram et al. 2007), while
most of hard red winter wheat varieties in the
USA originated from just two lines imported
from Poland and Russia (Tanksley and McCouch
1997).
The need to preserve endangered genetic
resources such as landraces and wild species,
coupled with an awareness that crop improve-
ments are based on availability of diverse
germplasm, led in 1983 to the founding of
the Commission on Genetic Resources for
Food and Agriculture. In 2001 the Interna-
tional Treaty on Plant Genetic Resources for
Food and Agriculture (ITPGRFA) was adopted,
followed by the establishment in 2004 of the
Global Crop Diversity Trust, a public and pri-
vate partnership that supports crop collection
maintenance with individual and government
funding ( http://www.croptrust.org). Germplasm
available today for breeding and research can
be classified into six groups: modern cultivars,
obsolete cultivars, landraces, genetic stocks,
breeding lines, and wild relatives; and these
can be subdivided according to the “three gene
pool” concept introduced by Harlan and de Wet
(1971). If we consider the potential usefulness
of those gene pools for improving frost resis-
tance, hexaploid spelt ( T. spelta L.) is known
to be more winter hardy than bread wheat, and
could be sown in regions with a higher prob-
ability of frost damage; however, it yields less
and is more difficult to harvest than bread wheat
(Milisauskas 2011). A number of A. tauschii
accessions were found to be frost hardy, but
not as much as winter wheat cultivars (Limin
and Fowler 1991). The research section at the
International Maize and Wheat Improvement
Center (CIMMYT) developed more than 1,000
synthetic hexaploid wheats, by using different
accessions of A. tauschii as D genome donors.
Synthetic hexaploids were resistant/tolerant to
different abiotic and biotic stresses (Dreisigacker
et al. 2008). However, the potential of syn-
thetic wheat for improving frost tolerance at
the vegetative stage was limited, that is, their
hardiness levels were similar or equal to that
of their hardy parent, with no transgressive
recombinants, as highlighted in early attempts to
deploy cold tolerance of amphidiploids (Limin
and Fowler 1982; Le et al. 1986). Neverthe-
less, more recently some synthetic hexaploids
were reported to suffer less frost damage during
the reproductive period (Maes et al. 2001). In
barley, high variability in tolerance to different
abiotic stress, cold tolerance included, could be
introgressed from the wild progenitor H. vulgare
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