198
8.1.3.3 Storage Proteins
Triticum monococcum contains allelic variation for storage proteins and unique loci
that could be used to enhance baking quality of bread wheat and cookies (Tranquilli
et al. 2002 ). The main locus is located on chromosome 1A m. Whereas the high
molecular weight glutenins of T. monococcum reduced cookie diameters and cookie
quality and increased sedimentation volumes, the low molecular weight glutenins
had opposite effects. Recombinant substitution lines between chromosome 1A m and
bread wheat chromosome 1A have been produced (Dubcovsky et al. 1997 ).
Puroindoline genes Pina and Pinb are mapped to the kernel hardness locus in
chromosome 5A m. These loci when transferred to hexaploid wheat (Bonafede et al.
2007 ) will result in softer-textured kernels which require less energy in milling and
reduced starch damage. The translocated segment has been defi ned by STS and
microsatellite markers. The hardness locus has been sequenced (Chantret et al.
2004 ). A grain texture-related locus in T. monococcum was further characterized
physically and genetically (Tranquilli et al. 1999 ). A new Mr (Low molecular
weight glutenin) locus has been mapped to chromosome 7AL in T. monococcum
(Dubcovsky et al. 1997 ).
8.2 Emmer Wheat T. dicoccum , T. dicoccoides , T. carthlicum ,
T. araraticum , and T. durum
Wild emmer was fi rst described by Aaronsohn ( 1910 ) after its discovery in Israel.
Its habitat is believed to be centered near Sanliurba in Turkey. The wild hulled form
is designated as T. dicoccoide s Körn otherwise known as wild emmer. The culti-
vated hulled forms are designated as T. dicoccum Schrank, commonly known as
emmer and T. ispahanicum Heslot commonly known as Ispahan wheat. As for the
cultivated free threshing forms, seven species are listed according to the Dorofeyev
system of classifi cation. The six species are T. aethiopicum Jakubz., T. polonicum
L., T. turanicum Jakubz., T. carthlicum Nevski, T. jakubzineri Udacz. and Shakhm.,
and T. turgidum L. (or Poulard wheat). All of the above species are thought to have
originated as hybrids between T. urartu and a B genome donor such as Ae.
speltoides or Ae. searsii , and all share the A and B genome. The centre of diversity
of the wild forms is considered to be in the Fertile Crescent around the Mediterranean.
8.2.1 Molecular Maps
The fi rst molecular map was constructed by Peng et al. ( 2000 ) in a population
derived from crossing T. dicoccoides with the durum variety Langdon. The total
map length exceeded 3000 cM. Genetic differentiation between parental genomes
was controlled by the B genome as determined by AFLP markers. Segregation dis-
tortion markers were mapped to chromosomes 4A, 5A, and 5B.
G. Fedak