Nucleolus organizer regions (Nor loci) of Chinese wheats

摘要

Nucleolus organizer regions (Nor loci) of a range of Chinese wheat landraces and cultivars (Triticum aestivum L. em Thell) were analysed using genonric DNA extracted from leaves. Only two allelic variants of the Nor-B1 locus were found on chromosome 1B (Nar-Bla and Nor-Blg), while Nor-B1g was probably introduced from North America in the early 1960s. The even more recent introduction of the rye allele Nor-R1 in the early 1980s was also revealed. Eight allelic variants of the Nor-B2 locus on chromosome 6B (Nor-B2a, b, d, j, h, o, p and s) were identified. A Chinese origin for the a, d, f, o, p and s alleles is evident although the d allele was successfully introduced into Australian wheats in the early 1900s. Nor-B2h and Nor-B2b are again very recentintroductions into Chinese wheat breeding programs, the former from CIMMYT wheats and the latter in association with the introduction of the 1RS/1BL translocation from Europe. On the basis of the presence of different combinations of Nor-Bl and Nor-B2 alleles, the Chinese wheat cultivars can be divided into eight phenotypic groups.