Comparative genome analysis among cereals as probed by DNA markers
1996
Ogihara, Y. (Yokohama City Univ. (Japan). Kihara Inst. for Biological Research)
I present here comparative studies of RFLP maps in cereal genomes (synteny maps among cereals), and applicability of DNA markers to investigate cereal genomes. Because of their sequence homology among cereal genomes, a common set of DNA probes were used to characterize and compare cereal genomes. These DNA markers clarified the extent of differentiation among closely related genomes, and disclosed conservation of chromosome segments among distant plant groups such as wheat, rice and maize. At first, we hybridized 75 rice genomic clones which were mapped on the rice chromosomes, to eight cereal DNAs. 56 clones (75%) were commonly detected in the eight cereal DNAs, indicating that the cereal genomes contain those sequences homologous to probe DNAs. 12 clones (16%) revealed positive signals only in the rice DNA, harboring rice-specific sequences. While rice-specific sequences were dispersed throughout the chromosomes, those commonly detected among the cereal genomes had a tendency to occur in clusters. Most of these clusters were conserved in the respective wheat chromosomes, showing syntenies. Although basic chromosome structures are conserved in polyploid wheats, genomes of allopolyploid differed with each other, and southern hybridization analysis for the copy number of plotosynthesis-related genes suggest that some mechanism(s) for keeping to a minimum the number of genes might operate in polyploid plants. Synteny of RFLP maps among Triticeae, and wheat-rice-maize are now disclosing by use of a common set of DNA probes
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