With the object of studying the genomic relationships of Brassica tournefortii Gouan with the other elementary species of Brassica viz. B. campestris (2n=20, A genome), B. oleracea (2n=18, C genome) and B. nigra (2n=16, B genome), it has been hybridized with them. The percentage of F1 hybrids formed, their morphology and meiotic behaviour have been described. Based upon crossability relationships and meiotic pairing in the F1 hybrids, it is inferred that the D genome of B. tournefortii is more closely related to the A genome than to the B and C genomes. It may have been derived from the A genome which likewise shows a strong genetic isolation from B and C. The species has developed a strong genetic barrier in the course of its evolution and shows little crossability, high hybrid sterility and no gene flow with any of the other elementary species. The fact that it has not formed any natural amphidiploids with the elementary species which otherwise are formed in all combinations, is more evidence that it originated more recently than the A genome. It is presumed that B. tournefortii, being more distantly related to B. nigra than to other elementary species, may form stable artificial aphid resistant amphidiploids with the former.
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Narain, A. & S. Prakash (1968). Genomic homology between Brassica tournefortii Gouan and other 20-chromosomes species of Brassica. Proc. XIIth Int. Congr. Genet., Tokyo 1: 181.
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Narain, A., Prakash, S. Investigations on the artificial synthesis of amphidiploids of Brassica tournefortii Gouan with the other elementary species of Brassica. I. Genomic relationships. Genetica 43, 90–97 (1972). https://doi.org/10.1007/BF00122502
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DOI: https://doi.org/10.1007/BF00122502