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Results and Discussion
Aminoacid composition of the analzyed species is shown in
Table 1.
Species did not show any difference for aspartic acid,
isoleucine, tyrosine; differences among species were
significant at 1% level for all the other aminoacids.
Correlation coefficients shown in Table
2 indicate that lysine was positively associated with
arginine, aspartic acid, alanine and negatively with
tyrosine ; histidine was positively associated with
threonine, serine, proline, glycine and leucine, while
arginine was associated to alanine in addition to lysine.
Leucine was also associated with threonine, serine, glutamic
acid and proline ; serine was associated also with
threonine, glutamic acid and proline ; this later was
associated with glutamic acid.
Results of canonical analysis indicate that the variability
accounted for by the first three characteristic roots was
over 93%. The fist characteristic root (47%) was positively
correlated with serine, glutamic acid and proline, the
second (39%) was negatively associated to glutamic acid and
positevely to glycine, threonine, serine, alanine and
leucine. The values of the first three canonical variables,
for the analyzed samples are graphically reported in
Fig. 1.
Two clusters seem to emerge from the obtained picture. The
first cluster is formed by T. speltodies, T.
longissimum and T. dicoccoides, and the second by
T. durum and T. aestivum. While the
relationships among these two latter were rather obvious,
the similarity (closeness) between longissimum and
dicoccoides seems to be rather interesting, although
expected. On the basis of immunochemical data and
Alpha-amylase inhibitors a possible involvement of T.
longissimum in the speciation of emmer wheats was
considered by KONAREV et al. (1976) and VITOZZI and
SILANO (1976) respectively. Isoenzyme patterns JAASKA
reporting (1978) suggested that T. dicoccoides could
represent a cytogenetically stabilized and evolutionary-wise
very successful recombinational segregant of a hybrid
between initial amphiploids, involving ancestral forms or
precursors of the contemporary diploids among which T.
longissimum.
Samples of T. monococcum represent a rather
independent cluster, which shows, by the second and third
characteristic roots, some closeness with the cluster formed
by T. dicoccoides, T. longissimum and T.
speltoides.
Worth of mentioning is also the fact that, according to the
second and third characteristic roots, T. tauschii
samples lie very close to the durum-aestivum cluster.
Since these two characteristic roots are considered to have
more biological meaning than the first one (BLACKITH and
REYMENT, 1971) and closeness of T. tauschii, donor of
D genome (KIHARA, 1944), to the T. aestivum, could be
considered as an additional indication of the reliability of
the aminoacid composition in studying species relationships.
Interesting for the implication it could have in practical
breeding seems also the rather large variation shown by
T. tauschii.
In conclusion, the present study of species relationships in
Triticum, based on aminacid composition, seems to
confirm some of the earliest hypothesis, and provide a
criterion of genetic affinity which, in cooperation with
other criteria, could allow inferences on evolutionary
relationships. However, due to the limited number of samples
utilized and species analyzed, additional studies would be
necessary before a definite usefulness of the method may be
assessed.
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