| Summarizing the above, the following conclusions could be drawn. 1) The
majority of C-bands recognized in both varieties were centromeric or interstitial,
the interstitial ones mostly proximal than distal. No telomeric bands were
found at all. 2) In both varieties each chromosome of the complement showed
a distinct C-banding pattern, allowing precise identification. 3) Each variety
represents a single C-banded karyotype without evidence of major intravarietal
polymorphism. 4) At the intervarietal level, the detected polymorphism seems
to reflect the parental origin of the respective varieties. Thus CARINA
barley inculding the genome of UNION (VOSA 1976) proved to be less banded,
fitting partially the pattern provided by VOSA in TIBET and by NODA & KASHA
(1978) in BETZES (paucity of conspicuous distally located or telomeric bands).
GEORGIA a more banded modern crossbred variety, showed some differences
by comparing our results with those presented by LINDE-LAURSEN et al.
(1982) in the same variety (different source and parallel breeding). The
concrete differencs regard 1) presence of bands at the secondary constictions
of chromosomes 6 and 7 (absent in our material) and 2) presence in general
of telomeric bands (completely absent according to our data). The contradicting
results forced us to examine the situation of a differential expression
of the constitutive heterochromatic regions according to the application
of different stains. Therefore we found out that when Giemsa stain was used
instead of Leishman the disputable zones could be detected. The same holds
for TULEEN's 346 barley (complete absence of telomeric C-bands in Leishman-stained
chromosomes) as manifested by FINCH & BENNETT (1982). C. C-banding patterns of Agropyron striatulum We report only preliminary results, thas is one banding karyotype established by handling plants from two populations collected. The conventional karyogrammic phenotype suggested by MOUSTAKAS & COUCOLI (1982) represents a rather symmetrical chromosomal set with median or submedian members, including two satellited chromosomes (the one with ST centromere). The C-banded karyotype (Fig. 1B) showed a uniform characteristic pattern, with rather gross telomeric bands, and complete absence of centromeric heterochromatic segments. The majority of chromosomes (1, 3, 4, 5, 6, 7) manifested telomeric bands in both arms, those observed in the short arms being evidently larger. Chromosome 5 in particular showed an additional sattelited band exclusively in the material of one population. In both populations, we observed cells heteromorphic for crhomosome 2. This means that one of the homologues in these cells was bandless. Obviously, the "banding style" observed in Agropyron characterized of conspicuous telomeric bands, irrespectively of the staining technique used, fits the typical pattern found in other cross-fertilizers, as Rye, Ae spel toides, maize (LINDE-LAURSEN 1978). Though the subject has not as yet been experimentally investigated, it seems likely that the clear opposite results observed so far in banding patterns between in-and outbreeders could be associated with chiasma frequency reported as higher in inbreeding systems (MACKEY 1970). The work has been partially supported by the Hellenic Ministry of Research and Technology (Research project No. 342.). |
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