When barley, as female, was crossed with rye a high proportion of fertilised ovules developed. Cytological studies on developing ovules showed that the hybrid endosperm failed to develop normally, but contained polyploid nuclei, chromosome bridges, lagging chromosomes and micronuclei. Development of the endosperm from tetraploid crosses appeared to be more successful than from diploid crosses. In most ovules the endosperm degenerated by one week after pollination. Most hybrid embryos aborted about 8 days after pollination. Lagging chromosomes and aiorowclei, observed in developing embryos from day 3 after pollination appeared to be responsible for loss of viability. A small proportion of hybrid embryos which appeared to be free of cytological abnormalities could continue to develop as long as the fruits did not dry up. When crossed spikes were sprayed with specified growth substances, plump, liquid-filled fruits developed, from which a small proportion of developing hybrid embryos could be recovered at 18-20 days after pollination. These could be transferred to culture without much difficulty. When spikes were not sprayed, fruit development ceased before embryos reached a size suitable for culture. Most of the embryos transferred to culture continued to grow, although most ceased development before reaching a stage at which they could be transferred to soil. One embryo gave rise to callus which was subcultured on a medium free of growth substances. Green and albino hybrid plants regenerated from this callus. The green plants, which are sterile, grow vigorously. By means of Giemea C-banding techniques it was shown that the complement consisted of 8 rye and 6 barley chromosomes. It appears that the molecular chromasome of rye Me successfully substituted for a me leolar chromosome of barley.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643423 |
| Date | January 1978 |
| Creators | Cooper, Katharine Vanessa |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14710 |
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