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Discussion

Overall, polymorphic variation of C-bands is prevalent on chromosome arms 1DL, 2DS, 2DL, 3DL, 5DS, 5DL and 7DL, which are similar to those reported by Friebe et al. (1992) and Hohmann et al. (1993). However, in the present study a large amount of polymorphism of chromosome arm 5DS and a few polymorphisms on 6DL were found, which is different from their reports. The results of comparison of the C-banding pattern of T. tauschii accessions from Middle East (including the varieties typica, meyeri and strangulata) reported by Hohmann et al. (1993) with that of Chinese T. tauschii, indicates that the nine Chinese T. tauschii from the middle reaches of the Yellow River are more similar to the variety typica, although some variation was found. The two accessions from Xinjiang are different from all the three varieties.

Compared with the polymorphic variation between the accessions from the middle reaches of the Yellow River and the accessions from Xinjiang, which shows a large amount of polymorphic variation, there is less variation between the nine T. tauschii from the middle reaches of Yellow river or between the two accessions from Xinjiang. The result is consistent with the evidence of esterase and RFLPs analysis in Chinese T. tauschii (Yen et al. 1983; Ward et al. 1995). The differences of C-band polymorphism between the accessions from the middle reaches of the Yellow River and the accessions from Xinjiang are significant in chromosome arms 1DL, 3DS, 5DS and 5DL.

Though the C-banding pattern of T. tauschii chromosome is similar to that of homologues of Chinese Spring, there are some differences. Modification of C-banding pattern indicates differentiation in the D-genome chromosomes between T. tauschii and Chinese Spring (Friebe et al; 1992, Hobmann et al. 1993).


References

Friebe B, Mukai Y and Gill BS (1992) C-bandig polymorphisms in several aeccessions of Triticum tauschii (Aegilops squarrosa). Genome 35: 192-199.

Gill BS, Friebe B and Endo TR (1991) Standard karyotype and nomenclature system for description of chromosome bands and structural aberrations in wheat (Triticum aestivum). Genome 34: 830-839.

Hohmann U and Lagudah ES (1993) C-bandig polymorphism and linkage of nonhomeologous RFLP loci in the D genome progenitor of wheat. Genome 36: 235-243.

Ren ZL and Zhang HQ (1995) A improved C-bandig technique for plant. J Sichuan Agric Univ 13: 1-5.

Ward RW, Yang ZL, Yen C and Kim HS RFLP-based genetic diversity in Chinese landraceas of Ae. tauschii and T. aestivum. (unpublished).

Yen C, Yang JL, Liu XD and Li LR (1983) The distribution of Aegilops tauschii Cosson in China and with reference to the origin of the Chinese common wheat. Proc 6th Intern Wheat Genet Symp, Kyoto Japan : 55-58.

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