| II. Alien Chromosome substitution 1. Corss the recurrent variety as male with the monosomic lines of Chinese Spring. Also cross the variety with the desired alien species of Aegilops, Agropyron or Secale. 2. Identify F1 monosomics (2n-1=41) and back cross them as female with recurrent variety. Grow intergeneric F1 and apply colchicine to induce amphidiploids, (2n= 56). 3. Select B1 monosomics from the backcross progenies and cross them as female with amphidiploid. 4. Identify the F1 monosomics with the alien chromosomes having the chromosome constitution, 20II+1I+7I. Back cross them with recurrent variety. 5. Grow the back cross progenies. Identify plants which are simultaneously monosomic for a specific wheat chromosome and an alien chromosome (20II+1I+1I) and self them. 6. Screan the selfed progenies for alien monosomic (20II+1I) and disomic (20II+1II) substitutions. In the alien chromosome substitutions initially developed following the proposed scheme it will not be known which of the foreign chromosomes has substituted a speciflc wheat chromosome, unless there are some cytological or genetical markes. However, the alien chromosomes can be identified by applying some cytological technique. |
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