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|Title:||Genomes in the evolution of polyploid crop species and hybrids|
|Presented at:||University of Leicester|
|Abstract:||Many of the world’s crop species are recent polyploids. The various genomes from the diploid ancestors (known or, often, unknown) interact, with variable effects on genome packaging and nuclear organization (together the nuclear architecture), chromosome stability and gene expression. This project used a comparative approach to understand the genome composition in polyploids, focusing on millets in the Panicum group, saffron Crocus, Brassica and Nicotiana. In situ hybridization using DNA probes was used to identify the chromosomes and antibodies to synaptonemal complex, DNA repair and chromatin structure proteins including histones, which allow the understanding of the modulation of chromosome behaviour depending on the ancestral origin of the chromosomes, were used. The ancestors of proso millet, P. miliaceum (2n=4x=36), were identified as P. capillare and being the same as one genome in the 4x P. repens by in situ hybridization and ITS sequencing. A cell fusion hybrid of Nicotiana x sanderae + N. debneyi was confirmed, with demonstration of chromosome loss, by IRAP markers and in situ hybridization. Saffron Crocus, Crocus sativus 2n=3x=24, was shown to not be an autopolyploid, but to include three genomes with somewhat different chromosomal and sequence characteristics. The alien lines of Brassica and Raphanus with the fertility restorer genes were identified with B. rapa carrying the two chromosomes of Raphanus carrying the fertility restorer genes. Furthermore, the meiotic pairing basis of the alien lines of Brassica and Orychophragmus was also observed which gives an insight into the meiotic pairing between two different species. The water stress resistant genes could be identified from Panicum and thus be utilized in better water usage of plants. It would be possible in future to develop a synthetic C. sativus and thus rescue its declining production around the world, thus improving its economic potential. The fertility restorer gene can now be introduced into the B. rapa species using various mutagens.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Biology|
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